They basically introduced a bidding system that lets drivers increase fares up to 5x Uber’s set price. Uber matches the rider with the driver who has set the lowest price, and then the next highest price...gradually dispatching up to the highest price as more riders request rides.
It actually benefits the drivers to have Uber set prices. Uber's revenue is a percentage of drivers' earnings, so prices that maximizes driver revenue maximizes Uber's revenue. It's very easy for individuals to set prices in-optimally which means they either lose out on surplus (priced too low) or can't find riders (priced too high).
To me, the most important aspects of independent work is to set one's own schedules, hours per week (0 for as long as I'd like), and not bound to work for any single company. Though I might be biased because of the disclaimer.
edit: grammar fixes
I wouldn't expect them to be able to prohibit being active on one service while not active on the other (except maybe if you've got committed hours, and working another driving job would put you over DOT permitted hours, as prima facia evidence that additional driving hours would be unsafe)
Amazon doesn't sell their app...it maintains partnership with businesses, and manages their business using technology. Why shouldn't Amazon employ their retailers, who power their app just as much as the developers who created it?
Also: Uber is set to announce 25% layoffs, but not a single driver will be affected by this. To the extent that Uber drivers are "out of work", it's because there are no riders requesting rides — but that's a direct relationship between buyer and seller.
Instead, the strongest argument in favor of classifying Uber drivers as employees is the fact that they are unable to set their own prices. On the flip side, Uber has been gradually rolling out a new feature that allows drivers to do just that, which makes that argument moot.