I don't think that is a good reason to say they are employees.
What happens when you look at it like this; A Uber driver must accept some % of request sent their way (any class), but if you want to be sent uber black request then you must have an appropriate car.
I feel like you are looking at it from a top down view, vs a bottom up view. I am not saying ether view is right or wrong. I just find it hard to follow the logic to how that makes them employees.
But I have struggled with the employee argument from the start, so I am a bit bias at this point.
A big part of why I think people feel the way you do is because the system is programmed, and automated. If i was a guy looking for contractors to do jobs for me naturally people who were more consistently available and that I have worked with in the past would get jobs before people who can only be available "whenever". The only difference is that was some sort of decision I made in my head vs a system who had thresholds programmed.
What I feel like uber has done is automated the process of hiring contractors for on the spot jobs. And somehow people don't like the automation of it, or the rules. I feel like the solution is simple. Don't drive for uber if you don't like the terms. Go get a taxi medallion if you want to make your own rules, or drive for one of the competitors.