Interesting discussions at Megan's and Matt's. I think Matt does an exceptionally good job of illustrating the arbitrariness of subsidies to car owners simply by outlining an alternative scheme. I've always been a bit baffled by a lot of libertarian's generally pro-car-centric view of transportation matters. Now, if cars, highways, roads, big parking lots, etc., really are the most efficient way to do things, all things considered, then sure. But I never get a clear sense from many libertarians that they grasp the extent of the subsidies, or the very significant crowding-out effects of our massively expensive state-supported auto-based transportation infrastucture.
Also, bikes. People complain about bikers breaking traffic laws. Well, I'm guilty, and I'm damn well going to keep doing it. A lot of traffic regulations make sense for cars, but just don't for bikes. For example, I ride home almost every day the wrong way up a one way street, and nobody coming the other way gives a damn. Why should they? I honestly don't give a fig about my carbon footprint (and anyway, since I'm not a breeder, I really should get carbon carte blanche). But I like biking because it's faster than driving — because I blow through stop signs, go the wrong way on one-ways, etc. Were I suddenly to become fastidious about heeding traffic laws intended to regulate cars, one of the main advantages of biking over driving would evaporate. So I think people who do give figs about carbon really ought to encourage bikers to break traffic laws, or at least promote EXTRA traffic laws for drivers, in order to increase the relative benefit of biking. How about intersections where four-way purple means you've got to stop unless you're on a bike? That would be pretty sweet.