Joking aside, the idea of private operation of public functions is an idea that goes back through Ronald Reagan to Margaret Thatcher. And the fact of the matter is an asset is better maintained by an entity that has a financial stake in it, over one that does not. Even those much-despised parking meters in Chicago actually work. (The one that I found that didn't--I called the 1-800 number and the technician was standing next to me within 15 minutes--you think that would've been possible under the old, government run system?).
Comparing parking meters to the united states tax payer built and user funded interstate highway system is comparing an ant to an elephant. And is silly as hell.