Why do they need cars?
because you can't walk to things.
Why can't you walk to things?
Because they're so far apart.
Why are they so far apart?
Because a) parking minimums mean more land is given to parking than the actual amenity, and b) zoning forces single-use and density maximums
Why do people want parking minimums and zoning restrictions like that?
Because it's annoying to drive through high density.
Why do they need cars?
on and on and on
It's not an option because we built an entire country for 2 ton beings that need 30 feet to move in a circle, rather than humans. Can ants walk across Manhattan?
Seriously, look at your standard US "shopping center" and it's almost entirely parking. The lots dwarf the actual buildings.