[ksplicer]

You're making the assumption that roads pay for themselves, but that isn't true at all either. Across the US cities are going bankrupt because they can't maintain roads and other infrastructure. California has a gas tax that pays 80% of road maintenance, the rest of which is often paid from local city taxes that drivers and non-drivers alike pay. Many cities are falling behind in road maintenance though, the true impact of which won't be felt for ~20 years. A hidden cost of car infrastructure is also that the low density increases the costs of other infrastructure maintenance, such as sewage, gas, and power. Good mass transit is ultimately cheaper for everyone.