Wouldn’t that stick out on Uber’s end? A driver that continuously accepts rides and then cancels them without completing a single one? They could just ban the driver cutting off his source of new clients.
There are other apps, though. The id system of the local apps are fairly lax, so the driver will just create another account. Besides, they don't always cancel rides. Sometimes they accept "manufactured" rides. E.g. once you've hailed a ride on the street normally, they might tell you to initiate a search through [ride-sharing-app] and then accept it (to maybe complete some quota that lowers their commission payable).
Beats me. Maybe they are too big to notice? Or don't care? I've done this more than once (and I don't take many Ubers). I end up paying less and the driver makes more money, so everyone is happy.
