Perhaps because we have a lot of land, we keep building outwards instead of upwards, apartment complexes may be a couple of stories at best at least around here. This is why we need a lot of fuel, it's because just about everyone needs a car to get to work and do other errands, and the spouse needs a car, and eventually in high school the kid may have a car instead of using the bus. And people want huge ass gas guzzling SUVs, Hummer and trucks because a sedan apparently doesn't have enough hauling capacity to haul their own huge McAss.
Everyone gets on the road at the same time going to and leaving work, causing congestion issues and wasting even more fuel.
Attempts to retrofit cities with light rail are futile.. you still need to drive to a station.