Problem is that American cities were designed around cars. Getting anywhere on foot, especially for those who live in suburban areas, is basically impossible.
I'm not saying you are wrong, because you are definitely right, but I just want to put some context/scale along side this.
28% of greenhouse gas emission comes from transportation. of that 28%, 58% of that is classified as light-medium duty vehicles (consumer vehicles). So ~16% (58% of 28%) of greenhouse emissions are from consumer daily life.
16% is pretty big. Id love to see a dent in that. However, another 48% of the overall greenhouse emissions is energy production (25%) and industry (23%), and I think that's another area we can probably hammer on hard, and should probably start there since its a considerably larger percentage, and the targeted base actually has funds to make changes.