[hydrogen18]

Correct, but I could go rent the cab for a flat fee and just drive it around for my own personal wishes if I wanted to. They might put some restrictions on it (don't drive outside the city, no interstate) but otherwise I'd be fine.

As far as medallions go, that is just the result of government regulation. Plenty of industries wind up being populated with nothing more than a bunch of rent seekers. The government sets up an artificial scarcity where there is none to control negative externalities. The fix is easy: require the license holder to be the one that actually uses it. No leasing to others. As far as I know, no one has done that for commercial licensing. Ironically for private licenses (fishing license, etc.) this is already the case.