It's commonplace for drivers to text you /through the app/ demanding you cancel if they don't want to take the ride after they accepted it (they get penalized if they don't accept riders when they're set to accept rides). Outside the US, they act like they don't understand English and if you start writing in the local language they curse at you. If they do show up, they demand extra money in cash or they won't drive off. Once they get marked in app as having arrived, /you/ as a rider get penalized if you take too long to get in the car and start the ride.
Inside the US, drivers will just tell you to cancel and they'll stay parked in the cell phone lot at the airport until you cancel. They often actively enjoy /not/ taking the ride, because as long as the app thinks they're in transit and you as a rider cancel, they don't get penalized and don't have to do more work. Had one driver literally call me and tell me they were on their lunch break and would come get me in an hour and if I didn't want to wait I needed to cancel. Uber changed their policies and app and now a rider cancellation automatically charges a $5 fee /as soon/ as the ride is accepted, regardless of circumstances, and the fee is partially paid to the driver. So drivers literally get paid to fuck with you. Uber support is also useless, because when you get credited in the app, the credits don't get automatically used and there's no clear way to apply them when scheduling the ride. I have ~$200 in credits that continue to build until they eventually expire and have never been able to successfully use them.
Since I mostly travel for work and Uber is tied into our company expense system, at some level I don't care. I'll use what the company tells me to and what they pay for, but if I travel personally I have stopped using Uber in favor of Lyft in the US, and local options/taxis elsewhere.
Oh, if the ride is cancelled by either party, you can't rate the driver. So good luck 0-starring all the extorters.