The real world unfortunately doesn't work this smoothly, servers crash, weird bugs appear in the software, networking issues happen, traffic increases(hopefully) requiring you to scale out. I'd suggest you invest in finding a consultant who can help you on short notice if things go bad and keep them on a retainer.
> How many customer service representatives will you hire? None - the app will just link riders to drivers, and they will take care of customer service. Bad drivers will get banned from the service.
Who does the banning? How is it decided they are banned? What if there is a dispute between a driver and passenger who will handle that?