> Really there’s no one solution that works at every scale

Get private cars out of cities. That works

Cities are more than just ultra dense urban cores and megacities. Cars work well for stand alone cities under ~500,000 people.

That said, America relies heavily on public transportation even in smaller communities we just call them school buses and ignore em. So cars aren’t the cheapest option even at these scales, but they can be quite convenient when there’s minimal traffic issues.

I live in Thessaloniki, where you can get pretty lucky: The city is built along the coast, so there's a large boardwalk spanning the entire coast, it's pretty broad and has a nice bike lane. You can cycle from one side of the city to the other in 20 minutes or so, and the boardwalk is so broad that pedestrians tend to have enough space to stay out of the bike lane. It's an extremely pleasant way of transportation.

If you cycle anywhere other than the boardwalk, though, Greek drivers are going to kill you, but I've developed coping strategies (using side-streets).