I think the best point here is that American cities are not walkable. We tend to prefer long main roads with lots of business off of them to central areas where all important businesses are in walking distance. Main squares are more conducive to public transit than main avenues, because once you get there, you can walk. This is, in my mind, one of the hardest problems to solve for American public transit.<p>The expense and environment I think would both almost solve themselves if public transit became more common. If it were the main way to travel, then the distribution of people on buses would match the overall distribution of people.