For most Americans, they can easily carve out 1 hour of TV a day. There's really no excuse for anyone between the ages of 10 and 60 to walk 15 minutes a day. Obviously there are outliers, as you said, disability issues, health problems etc.

But the vast majority of Americans eat way more than they should and don't give it a second thought. For most of America it's a cultural issue, not a physical or practical problem.