Well, I don't disagree at all, but would argue that it's kind of a circular dependency problem. Sprawl would exist without cars to be sure, but cars make it much easier to expand, which increases dependency on cars, which supports sprawl. Then the people who have moved outward use their cars to work in the city because there's nothing in the suburbs and a poorly designed city (or one that is dependant on the people with cars) prioritizes that.

As someone who walks in Manhattan, I see where you're coming from, but my experience differs. Specifically, 99% of the time I'm walking in Manhattan, I'm not trying to get somewhere on the same street or avenue I started on, so I can turn and walk along whatever block to avoid the lights. Plus (at least in the 40s), there are plenty of subway entries/passages where you don't need to pay but can pass through to get underneath the street - and buildings you can pass through as well. Of course, figuring out this maze is half the "fun" of walking in Manhattan.

In Singapore they are experimenting with putting all traffic beneath the ground in new residential neighbourhoods.