This comparison strikes me as bizarre. The medallion racket is lobbying politicians to use the force of the law to prevent competitors from doing business. What discordorama describes is paying people money to install and sign into your app. This is... either a poorly designed incentive system that was then fixed, or a clever campaign that gets a lot of future drivers through the earliest hoops and puts them in a position where it's easy to incentivize them to start driving. (Clever to the extent that that works.)
I can't see why you think there's a similarity, other than that you think they're both underhanded, and that they're both done by companies providing taxi-like services.
They have to ensure supply while they bring on new customers (has associated acquisition cost) if they acquire a customer and that customer isn't able to purchase anything from them due to lack of supply (or in the case of uber the price is too high because of surge kicking in) then that customer will churn forever, and potentially share their negative experience with their friends.
So basically, nail supply, grow customers, don't run out of cash before the whole thing is working.
If Uber's incentives for drivers result in a better experience for riders (shorter rides), isn't that a good thing?