There's also a pretty obvious mechanism for selection bias here regarding which type of situation we're going to hear about. Few people are going to write up a post saying "I got close to my bonus, and then I got more rides, and I got my bonus, and it was fine", whereas people who feel like they're getting screwed tend to be very vocal. So the existence of these stories tells us next to nothing.
Moreover, they have much more opportunity to do it since a strip club and barber salon have a lot fewer rented spots (ones/tens vs hundreds/thousands) and there is more ways Uber can be sneaky about it. (Oops sorry it took us 10 minutes to find you a passenger)
OH there's also the fact that Uber has the ability to arbitrage. Since the drivers who payed in are more costly to Uber to send passengers to than the drivers who didn't. Unlike the other industries you mentioned where presumably everyone has to pay in.
Poor Abi...
Kalanick and the bros did a hell of a job trashing the company reputation.
https://www.theverge.com/2017/9/8/16273378/uber-fbi-investig...
so many stories of not getting any rides when they get close to a promotional number of rides. You can't prove it but they are very suspicious that Uber does it