Although for all the countries of the world the 2030 Agenda has represented real challenges in terms of stimulating a different way of economic and social growth in relation to the environment and its exhaustible resources, we identify today real difficulties in achieving the SDGs, carrying out activities of any kind in relation to maintaining the quality of the environment, which is, unfortunately, a constant problem.

Identifying and correcting the discrepancies between environmental degradation and technological progress are also goals pursued both by governments and by researchers, specialists and practitioners. This is because gaps and shocks of all kinds that occur at the level of communities, geographical and economic regions are still risk factors for which even the most advanced econometric and mathematical models cannot generate immediate corrective or preventive solutions ^[1][2][1,2].

Therefore, the various measures adopted by most United Nations (UN) members to achieve the Sustainable Development Goals (SDGs) included in the 2030 Agenda aim to respond primarily to challenges related to social, economic and environmental issues, establishing sets of indicators to monitor the progress or regression of each country from a sustainable growth perspective. 

The successful implementation of the 2030 Agenda depends exclusively on the approach to sustainability, human well-being, economic prosperity and environmental protection by each individual country, and each geographical region, as the SDGs are considered to be a complex, constantly interacting system that must ensure a safe and equitable global operating space for all. Moreover, it is also important to note that no SDG can be implemented and cannot act in isolation, and therefore the achievement of the targets depends solely on how synergies are harnessed and how different trade-offs are addressed ^[3][4][5][5,6,7].

The global development of society imposes a set of common rules which are derived from the major problems facing the planet and which, if dealt with in isolation, can generate far greater risks than those identified so far. Therefore, under the aegis of globalization and the new concepts of inclusive growth, and global economic development, the 2030 Agenda was created as a first universal framework for all countries of the world, with the aim of contributing mainly to the eradication of poverty but also to the implementation of sustainable goals in all aspects of human life by the year 2030. With a set of 17 concrete goals, the 2030 Agenda is today the central pillar of regional, national and local strategies and programs and by no means appears to be a mere target.

From poverty eradication to the rational use of natural resources, the 2030 Agenda encompasses and details every aspect of human life, making it a universal/global benchmark. In this broad but detailed context, the 2030 Agenda addresses one of the most important issues facing the world today: reducing inequality within and between countries. It is certainly an issue that the literature addresses in various forms, as it is an extremely difficult and complex goal with seven specific targets agreed upon by the 193 UN member states. SDG 10, therefore, is the most interesting and wide-ranging global target, addressing a wide range of inequality issues ^[6][7][8][9,10,11].

Global and regional inequalities still affect people in the poorest countries, but the richest countries are not excluded from this situation. This is justified by the fact that inequalities between groups within the same society persist alongside inequalities between nations/countries. This is the reason for the understanding that inequalities are largely unjust and derive in large part from differences between societies and nations.

At the global level, the most plausible solution to reduce the phenomenon of inequality has focused on the implementation of global governance mechanisms that have been and continue to be contested because they cannot include aspects of understanding how each country has evolved historically as well as the position of each country in the global economic system ^[9][10][12,13].

Reducing existing inequalities must therefore become a priority objective of both national and international policy agendas, even if piecemeal approaches based on one-off initiatives aimed mainly at “helping the poor” may be successful. On the other hand, reducing inequality requires national policies for economic diversification, appropriate fiscal, monetary and financial strategies and social policies that target disadvantaged social groups, but which must also incorporate respect for nature as an essential principle of world sustainability in the medium and long term ^[11][14].

In this regard, recent studies ^[12][15] carried out at OECD and non-OECD levels, from the point of view of inequality and economic prosperity included health indicators by gender groups (men, women) such as life expectancy, causes of mortality and avoidable mortality, showed that significant gender differences in health showed a positive outcome for women. Relationships between gender inequalities in health and economic prosperity were also identified. Therefore, policies should focus on reducing income inequalities by gender but also in terms of avoidable mortality, such as reducing common diseases among young people.

However, inequalities in income and wealth are increasingly evident and are even widening. This is reflected in the fact that the top 1% of the world’s population now controls up to 40% of global assets, while the poorest half of the population owns just 1% ^[13][16]. Disparities are also wide within countries, including disparities in rural/urban areas, gender disparities, ethnic minorities, migrant status and disability ^[14][15][17,18].

The SDGs, while including a number of explicit and implicit solutions that address inequality, are often vaguely formulated, the targets are abstract, and the issue of inequality remains a central one, requiring fundamental reform of sustainable development thinking for 2030 and beyond. Moreover, the construction of poverty eradication and development within each individual state must include values and problem-solving frameworks based on the responsiveness of all bodies involved in achieving the SDGs ^[16][17][19,20].

In this context, SDG 10 promotes the idea of a society in which every person enjoys the benefits of economic growth, which may be evident in some countries, particularly those that have experienced rapid growth, but often even in these situations economic growth can contribute to growing income inequality, inequality of access to opportunities by gender, religion, caste and region. Improving the social security system, introducing and expanding social insurance schemes and establishing special funds for lagging regions can therefore be solutions to key problems of inequality ^[18][19][21,22].

Although “reducing inequalities within and between countries” is a goal in itself, which stimulates the global community to international cooperation, the current state of the planet shows that this goal is extremely difficult and complex to achieve. SDG 10, has a series of targets that address a wide range of inequality issues, including: achieving and sustaining income growth for the top 40% of the population at a rate above the national average, promoting the social, economic and political inclusion of all, regardless of age, gender, disability, race, ethnicity, origin, religion or economic or other status; ensuring equal opportunities and reducing inequality of outcomes, including by eliminating discriminatory laws, policies and practices and promoting appropriate legislation, policies and actions to this end; adopting policies, in particular tax, wage and social protection policies and progressively achieving greater equality; improving the regulation and monitoring of global financial markets and institutions and strengthening the implementation of these regulations, ensuring greater representation of developing countries in decision-making in global international economic and financial institutions, facilitating orderly, safe, regular and responsible migration and mobility of people, including through the implementation of planned and well-managed migration policies, implementing the principle of special and differential treatment for developing countries, in particular the least developed countries, encouraging financial flows, including foreign direct investment, to countries where the need is greatest ^[20][21][22][23,24,25].

At the EU level, the situation is similar to other geographical regions, although a number of positive results are evident, at least in terms of the income gap between rich and poor. This is because in the EU, for example, S80/S20 share ratio for 2019, the income share of the richest 20% of the population was almost five times that of the poorest 20% of the population ^[23][26].

On the other hand, according to the Annual Labor Force Assessment, the COVID-19 crisis is likely to cause a deterioration in the socio-economic situation of low-income households and other marginalized groups, such as migrants and minorities. This unfavorable situation is largely due to loss of income and rising prices but also rising health expenditure, which can disproportionately affect low-income households and can have a number of long-term consequences, such as a person’s ability to save, health and children’s education. In addition, the pandemic has had negative effects on children’s mental health and exacerbated social inequality. In the same vein, the European Platform for Investment in Children (EPIC) highlights wide variations between EU Member States and suggests policy options to address the childcare gap ^[24][25][3,27].

Not least, inequality and poverty are closely linked, and the distribution of resources in a country directly affects both the extent and depth of poverty. Thus, in 2019, 20.9% of the EU population was at risk of poverty or social exclusion, and the urban-rural gap in the at-risk-of-poverty or social exclusion rate was 1.1 percentage points. Specifically, 21.3% of those living in cities were in this situation, compared to 22.4% in rural areas ^[26][28]. Moreover, rural areas are much more at risk of poverty because of migration and limited access to services, infrastructure and education. Rural poverty, therefore, remains at very high levels in 2019 in some European countries, such as Bulgaria and Romania, where 48.5% and 44.3% of the rural population were at risk of poverty or social exclusion, twice the EU average. On the other hand, other countries such as Austria, the Netherlands and France have much higher poverty rates in cities than in rural areas ^{[26][27][28][29]}[28,29,30,31].

Equally important to mention is the fact that the concepts of poverty, inequality and further social exclusion need to be analyzed and justified from several points of view. This is because there is a complex of factors that influence the state of affairs in a country and in areas within a country, particularly those linked to the economic dimension; these are often problematic and influence the way social problems are tackled ^[30][31][32][32,33,34].

Not to be neglected in this context is also the issue of the problems and challenges caused by poverty and migration, which are not limited to a single country or region in most cases. Consequently, reducing inequalities between countries is now seen as an essential condition for resolving complex problems, which often take the form of sharing prosperity and reducing barriers of all kinds.

The coefficient of variation of gross disposable household income between the Member States has decreased over time, reaching 24.9% in 2019. Northern and Western European countries with above-average GDP per capita levels had the highest gross disposable income per capita, with Eastern and Southern EU countries at the other end of the scale, with gross household income and GDP per capita levels below the EU average ^[33][34][35][36,37,38].

It is also important to note that in almost all European countries, immigrants face a higher risk of poverty than residents, which calls for a change in the approach of European policies to their impact on the well-being of immigrants. In practice, issues such as immigration policy, labor market regulation and eligibility rules for social assistance need to be considered ^[36][37][39,40].

On the other hand, the current crisis caused by the war in Ukraine should not be overlooked, which has recently led to an increase in the number of migrants, especially from neighboring countries (Poland, Romania, etc.). All these aspects could radically alter the current and future state of inequality reduction in the EU Member States, bearing in mind a potential future economic crisis generated by the oil crisis. The high number of migrants will directly affect SDG 10 specific indicators such as SDG_10_60, SDG_08_20A and SDG_08_30A. At the same time, the overlap of the crisis generated by the increase in oil and food prices and the high level of inflation will decrease the financial means of the population and, implicitly, lead to an increase in the risk of poverty and social exclusion, with direct negative effects on SDG_10_10, SDG_10_20, SDG_10_30, SDG_10_40, SDG_01_10A and SDG_01_20A indicators.

Therefore, the social inclusion of non-EU citizens is still a major challenge for all countries in the world, even if we identify procedures for monitoring and integrating people in terms of poverty, education and employment in the labor market. In addition, reducing inequality also has as its point of reference the gap between people at risk of poverty according to income, and the gap is still wide. In 2019, for example, 38.6% of non-EU citizens were at risk of poverty compared to only 15.1% of residents of the country of origin ^[26][28].

Equally significant as an example is the fact that the employment rate for non-EU 20–64-year-olds fell by 2.6% between 2019 and 2020, compared to the rates in EU countries of origin which saw a reduction of only 0.5%, further supporting the gap between the two groups. The same changes in the negative direction for migrants can also be identified in terms of leaving the education system, especially in the 18–24 age group. These changes directly affect both the income levels of these groups and their employment in the labor market in the medium and long term, as well as sustainable human development in all countries ^[38][39][43,44].

Reducing inequalities between people is part of the process of sustainable human development, as it is well known that people from less developed regions and countries are always economically and socially vulnerable. Moreover, this category of people is also more resistant to change, which affects the sustainable balance of society ^[40][41][45,46].

In the same sense, with the aim of reducing inequalities between people, at the EU level, we also note that there is a high level of convergence between countries, which is efficient, but this is only evident when wealth levels are similar and when countries invest in the long term in the efficiency of their human capital. Consequently, this strategy contributes directly to improving economic and social performance and even to attracting foreign skilled workers. Overall, this implies higher productivity, higher levels of sustainability, and consequently a balanced society in terms of quality of life for all citizens ^{[40][42][43][44]}[45,47,48,49].

Another important approach to the problem of reducing inequality at the EU Member State level also considers measuring the quality of employment of minority students. Therefore, issues such as the employment rate, working conditions, pay and well-being of minority students can reflect the quality of life of this part of a country’s population. Identifying these outcomes contributes directly to creating better working conditions, meeting students’ basic needs in terms of pay and welfare, but also to incentivizing students to perform better, etc. ^{[45][46][47][48]}[50,51,52,53].

Alongside all the issues identified above regarding inequalities and how they are reflected in the reality of EU Member States, thwe researchers can also highlight the issue of climate change, which is, unfortunately, exacerbating the imbalances between states and between people to an increasing extent. This is because rising temperatures because of greenhouse gases are generating strong negative effects, particularly in low-income countries.

This is justified by the fact that the costs of mitigating climate change may slow down the economic recovery of less developed countries and thus reduce inequalities between countries.