One of the biggest uses of public land is for transportation. Since transportation is used directly or indirectly by everyone, there is usually a public policy to subsidize transportation. Usually people don't think of this subsidy, unless they are talking about mass transit: the subsidy to transit is mentioned, while the subsidy to private automobiles is ignored. Some of the examples of subsidy to private automobiles are: the land used for roads and parking is not taxed; the pollution and congestion that automobiles cause is not paid for by the motorist, but by the population in general, whether they so pollute or not; the tax on new cars (at least here in NC) is less than the tax paid on other items.
Another large subsidy to automobiles is mandated parking: a person who wants to build a house or business must provide parking, usually for the worst case that that business or house would need. This ensures that many businesses do not open and many houses are not built, because the owner or builder doesn't have the land available to provide it, or cannot afford to provide the $15,000 or so per parking space that a parking deck would cost. Those who do provide this mandated parking simply add that cost to the cost of their product, so that everyone who patronizes that business or buys that house, has the cost of parking added to their bill, whether they use the parking or not. This ensures that people will drive even if they could walk, bike, car-pool, or take transit, because they perceive that driving is so cheap. This in-turn creates more demand for street widening, and subsidized parking.
So the question is: whose parking do you want to pay for? If we have mandated parking requirements for businesses or residential units, this will mean that you will pay for everyone's parking, whether you use it or not. Worse than that, mandated parking means that housing is less affordable, because the price of a parking space is included in the unit, whether the person needs it or not. The has a disastrous effect on people of lower income, who see the cost of housing increase as more requirements are put on housing.
Donald Shoup has written extensively on this topic; he has spoken here in Raleigh and his talk is available here.