As an aside, this is why I generally trust public transit more whenever it's an option. The worst case scenario is just so much less sinister when there are other people around than it is in a car alone with a stranger.
[0] once in a lyft in seattle, the other in a taxicab in barcelona. figuring I've taken about 100 lifetime solo car rides with strangers which is probably an overestimate.
How would uber know? They can’t unless someone reports the driver or gives them a poor rating.
This is my biggest problem with taxi service in the past. Unless they behave criminally towards you and you can go to police, you were at their mercy. Any cost had to be accepted, no idea how much it would cost upfront.
There were whole scam rings around that in some parts of Europe, taking foreign customers via very elongated roads to destination. Or a story from a colleague - taxi driver in Paris literally threw out a customer in the middle of highway since he didn't like his personal political views on famous french protests. In normal situation that would mean the taxi guy losing his 200k euro medallion, in reality of course nothing, zilch, nada.
FWIW, the oversight of Uber on drivers is part of the success of Uber. I'm not talking about their mistreatments of drivers, but the fact that as a consumer I have reasonable confidence that the driver has been doing a decent job so far and that if I have a problem with the driver, there'd be some consequences through Uber.
It's part of what allowed their success: from unaccountable taxi mafias to a service consumers can trust.
It's far from perfect of course but it's good enough that I'm confident enough using Uber (although I avoid it for other reasons) even in foreign countries. It's probably not impossible to achieve with a co-op, but it seems more difficult