Do you work in SDC development?
There's a difference between making it work for a small suburb area in Phoenix some of the times and making it work everywhere all the time. And the problem with ride-sharing applications is that unless it works everywhere nobody is going to use it.
Making it work everywhere for all circumstances is hard. Like really hard. There's a difference between an intervention-free ride and an actual ride that's both safe and comfortable. You could rack up your miles per safety intervention by programming a paranoid robot that sits at a highway ramp for hours without merging.
Is it possible? Maybe. It's nice that some deep models can magically (with no theoretical explanation) recognize a pedestrian, a vehicle, a bike. But would you trust it with your life? There's no theoretical safety guarantee unlike aviation where you can actually read and understand the proofs. I mean yes it could certainly work somewhere some of the time, but believing that it will eventually work everywhere all of the time is rather naive.