It's mostly cultural I suspect. There are almost no technical reasons and very few financial reasons why it wouldn't be possible. But to get there you'd have to

It's mostly cultural I suspect. There are almost no technical reasons and very few financial reasons why it wouldn't be possible. But to get there you'd have to make cities (as that's where those ares are the most useful) a bit more like Europe and Japan (for living, not for driving around in a big car), and people don't like change and in the US it's even more of a dislike it the change seems to come from an example outside of the country. Most of this suspicion is cobbled together from my own experience in the US (mostly the costs, not the middle part), and publications like NotJustBikes and about the way some US cities tend to grow outwards because investing in making what's already there healthy to live in is not as profitable as waiting for gentrification-ripeness and building around it in the meantime.