You might be interested in reading the recent posting by Tom Vanderbilt on his "Nimble Cities" blog and web site at Slate. The central issue in this particular article involves the long-standing local policy of requiring a relatively large number of parking spaces to be set aside by developers whenever new development is being done. The article does a nice job of tracing the origins and practices of this policy, and of highlighting some of unfortunate consequences. Perhaps most important among these, from a sustainability point of view, is that the parking space requirement subsidizes the use of the automobile, and has the effect of influencing more people to drive than might otherwise be the case. It cites some preeminent transportation scholars' work that documents the myth of "free parking."
Of course, the transportation issues raised in this piece are really about the connection between local public policies and the ability of cities to try to become more sustainable. It is yet another example of a set of policies that cities pursue that undermine any chance of trying to encourage people out of their cars.
Vanderbilt's article didn't really get too deeply into the root causes of these policies, but it is clear that there are two political motivations for cities to enact and implement policies requiring large numbers of parking spaces. The first is pretty obvious -- people want what they perceive of as free or low cost parking. But the second is not so obvious. Adding the parking space requirements to development ultimately increases the cost of development, and probably ensures that there will be less development. And that, of course, is what the "no-growth, slow growth" sentiment that exists in every city really wants -- less growth of any kind. Whether local policies can be changed in favor of more "smart growth" options in the face of such sentiment is a key political question.