On-demand mobility services provided by transport network companies (TNCs) have experienced significant growth in their adoption and diversification of services in major metropolitan cities around the world. This study analyzed primary data from Singapore to explore the sociodemographics of TNC users and determine who among TNC users is more likely to pool their trips and what modes these services are replacing. We compared these results with a comprehensive literature review of similar studies of TNC users in the metropolitan US. We found that the sociodemographics of TNC users in general are similar in Singapore and the US: younger, highly educated, and higher income individuals are more likely to have used TNC services. On the other hand, when differentiating by type of TNC service, we found that younger individuals from households that do not own a car are more likely to have pooled in Singapore, whereas employment is an important predictor in the US. We also found differences in mode substitution; whereas TNC trips in the US primarily induce additional trips or replace trips by public and non-motorized transport, in Singapore they primarily replace personal/private vehicle trips. In Singapore, we explored mode substitution by exclusive and pooled TNC services separately, and found that pooled trips draw more from public and nonmotorized transport, whereas exclusive trips replace more personal/private vehicle trips. These results suggest that people in Singapore view exclusive and pooled TNC services as distinct travel options that may be more closely related to other private or public transport, respectively. Differences between Singapore and the US highlight the importance of accounting for local context and suggest that the quality of all travel alternatives in the urban area will affect the mode substitution of TNC trips.