I think that if we were to follow that reasoning to the point of eliminating public transit, it would have to be eliminating all public transport subsidies: if all roads were toll roads and the tolls needed to cover the full cost of building and maintaining the roads, and there was no public parking, i think private mass transit would probably be successful.

(not that i think going that far would be a good idea. But it's important to realize just how much public money is spent maintaining infrastructure for private vehicles. eliminating free parking would be a very small portion of the subsidy.)