When I first arrived in Des Moines, I lived about 2 miles from my work in a suburb. When I arrived, I intended to either walk or take a bus to work, since I had no money for a car. I started doing this for a while, but felt severely out of place, since no one -- and I mean NO ONE -- uses the sidewalks in this suburb. For me, 2 miles was definitely doable, but somehow culturally taboo.
What I observed was that most people didn't walk because they had no idea of what a walkable distance was. Their automobile use prevented them from understanding what distances require a car and what distance can be done by bike/walking.
Years later, I run into quite a few people who say they would like to walk (bike or whatever...) to work but...
Of course, there are many reasons for this. However, sadly, most people don't do enough walking to even fathom what a walkable/bikeable distance is.
Have you observed this?