> I would argue that it is less due to politics and "safe streets" being an extreme position and more to do with the fact that _entire metropolitan areas_ are designed around the car.
These are the same thing.
> It would literally require starting from scratch in many places to design a city around non-car ownership.
No, it wouldn't. This is part of the common set of myths that are promulgated around car dominance in America. There are many, many things that can be done to retrofit streets to be less oriented around car dominance, many of them not terribly expensive or time consuming (though admittedly the very best options do tend to be infrastructure that's expensive and time consuming).
For example, one thing Portland has done in some of its neighborhoods is to create neighborhood greenways, with concrete structures/blockers at some intersections that force you to turn, so that cars can't use the street as a 'through street' for commuting (but it's still possible to reach everywhere with a car for residents). This is fairly cheap and easy to do, it's just a matter of political will.
Here's an example picture (though the exact type of blocking structure can vary): https://www.portland.gov/sites/default/files/styles/max_768w...
This is a big improvement that doesn't require redoing the whole street or anything, just a few concrete dividers and a little paint along a street maybe every four or five intersections, enough to make it impractical to use for longer-distance car commuting.
Some other things that are usually relatively cheap to add to existing streets:
* Automated speed cameras
* Roundabouts
* Chicanes
* Protected bike lanes, using basic dividers
* Dedicated bus lanes
* Better bus stops that at least have some kind of roof and bench
* Zoning rule changes that play well with density, like allowing light retail in currently residential-only zones, or allowing 'missing middle' housing
These are off the top of my head, but I know there are more.
