Accessing them is provided by the digital platforms related to Mobility-as-a-Service (MaaS) ^[1][3]. The presented SMS is defined as a type of the real-time car sharing based on location. The provision of these services is based on using geographic information systems (GIS) and technologies of global positioning systems (GPS) ^[2][4], combined with mobile technologies to organize shared rides arranged between drivers and passengers. Digital SMS platforms allow individuals using their car to transport others in return for a fee. In order to book a ride, customers use a smartphone application where they can additionally track the location of the required vehicle. Payment is usually made via the app at the end of the trip. According to Transit Cooperative Research Program (TCRP) Report ^[3][5], the shared-mobility service has become one of the most ubiquitous forms of car sharing. The term “shared mobility” was introduced to describe a car-sharing service (i.e., a ride-sharing service which combines more than one trip) ^[4][6]. The Shared-use Mobility Center ^[5][7] states that Uber, established in 2009 by G. Camp and T. Kalanicka, has been the largest company providing such services to date. The Uber app was officially launched in 2010 in San Francisco. The Polish branch of Uber was registered in December 2013 as Uber Poland spółka z o.o., and on 19 August 2014, Uber started offering its services in Warsaw. Outside Warsaw, it can be used in Poland by the residents of Krakow (since April 2015), Tri-City (since June 2015), Poznań (since November 2015), Wrocław (since November 2015), Łódź, the Silesian Agglomeration and Szczecin (since September 2020). Uber offers various service packages, the available services in Poland are as follows: UberX, UberXL or UberSELECT (economic rides), UberSUV, UberBLACK and UberLUX (premium trips), rides for people with disabilities, UberPool (shared rides). Since 2017, the UberEats service (the possibility of food delivery) was introduced in Poland. Currently in Poland, Uber has a 50% market share of the rides ordered via applications ^[6][8].

The technological factor ^[7][9] and the issues of positive influence on sustainable development were initially recognized as the primary driver of SE growth, whereas a car as a resource not used by its owner became, in 95% cases, next to a power drill, a flagship example confirming the contribution of the sharing economy to sustainable development ^[8][10]. However, Gerwe and Silva ^[8][10] suggest taking into account the individual preferences and characteristics of those using the discussed services when estimating the total net impact of the car sharing services on sustainable development. It is only when the individuals decide to act as responsible consumers and take sustainability seriously that they become engaged in appropriate actions ^[9][11]. Responsible consumers take into account the social, environmental and economic impacts of their consumption ^[10][12]. Responsibility is becoming an important dimension of attitudes and behaviors as well as the determinant of their market choices ^[11][13].

2. Shared-Mobility Motives

Shared-mobility service companies, including Uber, offer innovative and cheaper transport alternatives by reducing the marginal cost of service provision. These platforms are developing dynamically, offering a variety of services to meet diverse needs. Uber offers prearranged and on-demand transportation services in which drivers and passengers connect via digital applications, which are typically used for booking, electronic payment and ratings. Uber is included among the digital platforms related to MaaS. They enhance changes in social behavior in the market, which can be defined as transformations in the consumption model, i.e., moving from owning towards sharing ^[12][13][14,15], although as emphasized by Barbu et al. ^[14][16], neither of these consumption patterns are going to fade away. In their opinion, they will continue to coexist, expanding the range of the available consumer options. From the perspective of a user, SMS are developing very dynamically primarily due to: the application availability and its many functions (e.g., new user data verification process through the application), user safety (monitoring drivers’ driving and the control of trips made), user data security, payment data security and mobile application use security ^[15][17]. The research addressing SE is dominated by the studies covering accommodation and transportation services, where the authors’ attention is mainly focused on Airbnb and Uber platforms. The source literature on Uber provides analyses of the business model and factors behind its market success ^[16][18]. A frequently addressed research problem is the effect of introducing Uber to urban transport systems in different cities ^{[17][18][19][20][21]}[19,20,21,22,23], taking into account the environmental impacts ^{[22][23][24][25]}[24,25,26,27] and also the employment factor ^[26][28]. Much attention is paid to the issues of policy towards Uber and the regulations underlying its activities ^[27][28][29][29,30,31]. The motives are described in literature through the prism of many theories, the earlier ones such as, e.g., Maslow’s Hierarchy of Needs or Herzberg’s Motivation theory as well as the contemporary theories of motivation (e.g., Expectancy theory) ^[30][32], Acquier et al. ^[31][33] and Möhlmann ^[32][34], who proposed a division into external and internal motives, and Dann ^[33][35], who conducted a decomposition of push and pull motives. The theory of push and pull motivations is often used in the studies on motivation in tourism. People travel because they are propelled by the psyche (push) and drawn by external forces (pull) ^[34][35][36,37]. As Hossain ^[36][38] states, motivation stands for an essential issue when it comes to the success of SE initiatives, hence the motives represent an important problem in research where the authors’ attention is focused both on the service providers and customers. Additionally, consumers’ motives are identified in terms of users—non-users and, as shown by Hawlitschek et al. ^[37][39], non-users’ motives are analyzed much less frequently. Most of the studies cover the accommodation sector. According to the analyses by Böcker and Meelen ^[38][40] and Hossain ^[36][38], there are gaps in the research on the motives followed by those using car sharing services and, as emphasized by Sung et al. ^[39][41], few of them discuss the motivations related to using platforms from the consumer’s perspective. At this point, it is important to highlight the significance of focusing on the motives in various SE sectors, because as the research findings by Böcker and Meelen ^[38][40] show, they remain diversified depending on the analyzed field.

3. Sustainability

Sustainable development has been identified as one of the greatest contemporary challenges. Based on the review of the previously published papers on sharing economy, Ranjbari et al. ^[40][42] stated that sustainability is an important concept applied in research. According to the authors, shared mobility offers great opportunities for supporting sustainable development ^[21][23]. In the opinion of many researchers, sharing the unused resources contributes to the efficiency improvement of their use. In other words, SMS should result in both economic (additional revenues and savings), social (access to services, convenience, additional functionalities) and environmental benefits (reduction in energy consumption, greenhouse gas emissions, PM2.5 pollution and traffic congestion and noise) ^{[1][41][42][43][44][45][46]}[1,3,43,44,45,46,47]. However, there is evidence that this positive impact of sharing on sustainability is not an unequivocal one ^[46][47]. Barnes et al. ^[44][45] indicate that the effect of reducing PM2.5 emissions may be temporary. The researchers analyzing one selected first-order effect usually resulting in findings confirming the positive impact of car sharing on the environment, society or economy ^{[42][47][48][49]}[43,48,49,50]. In turn, those who perceive the problem in a broader perspective (second-order effects) are highly skeptical about this positive influence, e.g., Jung and Koo ^[46][47]. According to Codagnone et al. ^[50][51], in practice it has neither been sufficiently transparent nor reliably documented. Demonstrating the net impact in terms of environmental sustainability at an aggregated level is extremely difficult and complex ^[51][52]. As some researchers claim, the problem of economic effects of SE development as well as social and environmental issues should still remain the subject of scientific studies ^[52][53][53,54]. The source literature provides interesting analyses addressing the problem of sustainable development in the behavioral context of the sharing economy participants. However, they have certain limitations, because they refer to one selected market segment (quite frequently to generation Y) and/or one specific location (e.g., a selected city in the USA), as well as one sustainability pillar alone (e.g., related to the natural environment). The literature discussing Polish users of digital platforms offering transportation services provides the research covering young people using BlaBlaCar ^[54][55]. The recent analyzes, in turn, refer to the residents of Łódź using bikes offered under the municipal rental system ^[55][56]. While carefully comparing the results of these studies, and being aware of the limited possibilities for making such comparisons, the discrepancy in the conclusions formulated by the researchers becomes noticeable. Based on the results of empirical studies, some researchers confirm, e.g., the importance of environmental aspects related to using shared mobility, whereas others deny it ^[56][57]. Overall, it should be stated that the impact of environmental awareness of consumer behavior in the case of SMS ^[38][57][40,58] and the motivations for using Uber services have not been sufficiently analyzed as yet.