Well, I'm a Latinamerican, and we kind of hate people from the US are called American, but that term is kind of shitty since everyone in the Americas are American, so they are appropriating of something it's not only theirs. In Spanish that word doesn't even exist, we use "Estadounidense" which translates to something as "Statesian", but in my opinion it's not that good of a term. In Esperanto there's the word "Usono" which means the same, so I adapted it more to an English style "Usonian". There's a really good song by Residente, who previously was part of Calle 13, that talks about this, and he did it as a response to Childish Gambino's "This is America". Its English subtitles are pretty decent, so you can listen to it that way. https://www.youtube.com/watch?v=GK87AKIPyZY

As far as I know, it's a Frank Lloyd Wright thing about radical decentralization/individualism.

Most sources on the web are unhelpful because they only talk about it as applied to architecture, but he had a bunch of ideas about urban planning (or rather, anti-urban planning) that are much less well known and get drowned out in the noise.

Here's one half-decent article I've managed to find about it

The TL;DR is that Wright liked the idea of basically replacing cities with endless suburbia/Jeffersonian hobby farms interspersed with small towns, such that everything would be self-contained/self-sufficient. Or something like that, anyway. (In hindsight, the legacy of Wright's idea is that American society took the "spread everything out" part without the "and get rid of cities" part and invented disastrous suburban sprawl.)

Anyway, I think "usonian" is being used here to allude to the idea of failing to provide sufficient Federal funding for infrastructure because of misguided individualism, maybe?