Don't people walk in America?
In most places the answer is: not if they can help it.
Other places (Los Angeles being the capitol of this, but thousands of suburban areas followed them) are designed/planned to actively discourage it. In LA there are lots of things where if you are on foot (or bike) you literally 'can't get there from here.' That, and LA cops will slow down to roll on you, since if your walking in LA you must be guilty of something else too. In LA, walking around - openly advertising that you don't have a car - is the equivalent of walking anywhere else without pants on. It gets you noticed, and by all the wrong people at that.
There are a few places, either by design and/or geography, that are real 'walking cities' - Boston, New Orleans and lower Manhattan. And there are places that have OK public transportation and where parking is so bad that you are discouraged from driving, like metro Chicago. And a few places with both - like San Francisco. There are a lot of college/university towns that are designed and built for use by humans as opposed to cars, but that kind of visionary thinking is confined to the academic area (the campus, student housing, student services and business) and rarely extend past that area.
