This is probably one of the most insightful comments in this entire thread. Density isn't the problem - zoning is. Even in a suburban area, if there was a corner store, you could just take a golf cart, provided that you live someplace with a climate like the West Coast. I live in an area that swings from -5f in the winter to +105f in the summer, so for many months out of the year any transport without HVAC is not something you'd actually want to use.