Just because the process is automated doesn't mean that no negotiation is taking place. Uber drivers negotiate all the time, every time they shut down the app due to rates being too low at the moment they negotiate. So Uber is forced to set rates at levels where they have enough drivers and enough passengers. It isn't like a job where if you just stop working they will fire you, you can drop in and out of uber whenever and however you want as long as it isn't in the middle of a ride.

I mean, imagine if a McDonalds worker could just say "I don't feel like working for $10 right now, I'm going home!", and then just leave in the middle of a shift. Then the next day he sees that Burger king pays more, so he goes and work for them that day for a couple of hours, after which McDonalds increased their rates so he goes back there and work a few hours. Sounds like insanity to you? Well yeah, because it is insanity if employees could act like that!

Uber drivers are not employees, end of story. Uber doesn't have any power over them as is, normal workers have a contract which is worth a lot to them, you have no such contract with Uber as it is trivial to get the permit to drive for Uber, Uber drivers are not afraid of Uber suddenly firing them, they can go in and out of their role how much they want.