I think the real issue is that people are just incredibly lazy. My area isn't "walkable", but its what I could call "walkable enough" -- you can get a meal and a hair cut and lots of kids could walk to school. Of course, the sidewalks are empty here. Just an occasional cyclist. Even areas around here that are much more walkable like a grouping of shops, people all seem to prefer driving shop to shop! We're talking like maybe 100 meter walk max. Cars are the default, and if you suggest walking, you get looked at like you're nuts.

These same people don't even like cars or driving. I think they just like a comfy seat and air conditioning.

The car is basically a mobile sofa to the population. Shove them into the crappy cars of the 60s and 70s with no A/C and I think they start walking a bit more.

It just comes down to time. I can drive to the store in 5 minutes, or walk there in 20. Then I have to carry it home. You can call that lazy, but there are only 24 hours a day and a third of them are spent sleeping, a third working, and so that last third is precious.

The reason it takes 20 minutes to walk to a store is because of the automobile. I live in SF, and very few areas of the city are more than a 5 minute walk away from a grocery store. The problem of the automobile is a problem of development and saturation.

The automobile is ideal when few have them. This is exactly why the proliferated widely, now that we have 1.8 automobiles/household, the problems of automobile culture are inescapable unless we revert areas of our cities to pre-automobile urban design.

Cars are arguably one of the most important inventions in recent history. So much of what we have today would never have happened if we still had to walk everywhere.