The medaillion system is weird, but it works in new york.
The people who think that the invisible hand of the market would improve cab service are awesomely naive. The reason why cabs aren't fucked up in NYC is because of all the regulations, which can only be enforced because the cabbies have something to lose (the mediallion). If there was no government interference, cabs still wouldn't take credit cards, they wouldn't pick up non-white people, they wouldn't drive you to Brooklyn, they would form their own cabal and eventually rip out their meters and just make up whatever price they wanted to charge you, once you got there.