"Yet somehow nearly no one in America is aware of this or concerned about it. I wish I understood why that is."

I can't speak for everyone but in my case it is because I grew up in an impoverished community that had little to no zoning.

I experienced first-hand what the built environment is and the emergent behaviors of people are when there are no rules.

See, you live in a place that is nicely organized and, presumably, zoned and you think if we got rid of the zoning then everything would be just like it is now but with a few more housing units and maybe some delightful mixed light-commercial interspersed and wouldn't that be great!

In reality what you get is a welding shop next to your house. And llamas. And people disconnecting from city sewer because by god they're not paying for that when their home-built septic works just as well. And Grandma died and what do we do with her horse I know we'll keep it in the front yard.

If you had any exposure to anything other than nicely zoned locales you wouldn't romanticize the absence of rules.