route planning / fleet management i think is a huge optimization problem. perhaps you can cut it for MVP but it would require having a big multiple of drivers to provide the same service
another big deal is gps accuracy in cities, which is a pretty non trivial problem but at this point a consumer expectation https://www.uber.com/blog/rethinking-gps/
Ahhh yep. I remember Uber 2010 unopinionatedly just setting the pin directly on whatever the reading was from GPS. Stale or inaccurate GPS readings led to so much confused communication between drivers & passengers.
another big deal is gps accuracy in cities, which is a pretty non trivial problem but at this point a consumer expectation https://www.uber.com/blog/rethinking-gps/