Not just in NYC, this is an almost universal element of taxi regulation. The city will either require that taxi companies operate a certain number of ramp taxis

Not just in NYC, this is an almost universal element of taxi regulation. The city will either require that taxi companies operate a certain number of ramp taxis as a condition of their medallions (thus implicitly subsidizing them off other taxi rides) or directly subsidize operators of ramp taxis. The State of California recently required all of the ride-sharing companies to produce reports on how they "planned" to accommodate disabled riders, but so far as I know, nothing has come out of it.