I think the thing to keep in mind when considering payment methods is the country in which you are operating and its norms.
For RSS providers like Uber, they will be operating in a number of different markets and a one-size-fits-all approach to payments may limit their success in some markets.
New Zealand is a relatively cashless society for the most part — we are used to using EFTPOS or credit cards in a lot of situations. I recently attended a craft market where the website warned attendees that some stalls would only accept cash and there was also a special cash withdrawal stall as the assumption was that a large number of people would not be likely to be carrying cash with them. I feel in New Zealand this is also a fair assumption to make.
This means that for a New Zealand audience, expanding payment options to cash may not significantly broaden your potential user base. However, expanding payment options to include EFTPOS could potentially have a bigger impact on potential RSS users.
It is the typical conundrum faced by global companies — what should or shouldn’t be localised? I think that RSS could benefit from offering some localised payment methods that are tailored to each market. Would these benefits be worth the cost of rolling out a custom solution to each market? I’d suggest RSS would need to investigate and make a decision on that. My instinct suggests that it probably would be worth it for large markets with cultural differences where there is a demand for different payment methods (for example India or China may fall into this group of markets), but probably not for other countries that are relatively cashless and likely to adopt Uber’s existing method even if they gripe about it a bit (for example New Zealand and Australia are likely to typify these markets).