And this guy was talking shit about Uber. Motherfucker, if you didn't have to pay $1600 A MONTH just to drive your shitty taxi, then you could compete with Uber. Why don't you petition for that? Well, the reason behind this is that The City did think about this at one point but because there is a market value associated with the plates they would end up getting sued by the plate owners.
Sooner or later (sooner), those plates will end up having no value and will not be used anymore.
They probably should have done it and paid them off to avoid the lawsuit - would be cheaper but would look like nothing other than a bribe, which is kind of what it would be on one level, but also some compensation for actual value that your new regulations would be removing.