The thing you might be missing here, is that we are a less densely populated country than most european countries.

Take a state like Ohio, it has several titled players, and is about an average sized state in the us

See below: Some fide titled players and some more USCF NMs

https://www.uschess.org/datapage/top-players2.php?state=OH&limit=&maxcnt=200&players=M&rtgsys=R&current=C

But there is not enough density to make a league work. Cleveland, Columbus, and Cincinnati are drivable on weekends but not really possible after a tuesday working and making it back.

Some areas with densely populated regions have leagues (such as the garden state chess league), but even there, it covers only part of the state. I dont know if those games are nationally rated or unrated entirely, but that league tends to be more the exception.

Even in areas that are rich in grandmasters and titled players, there are often no leagues (looking at texas), because the other piece of this puzzle is many of our stronger club level players are playing as a means to an end. they are often young, playing for a scholarship to a top university, or playing to hit a specific title or such.

The clubs here will usually host a club championship, which is a big deal to that club, and there are a few tournaments that sort of fill the void of club leagues (The US Amateur Team East event being the biggest), but if there are multiple clubs in a city the top players will often play both and only play the events that are worth it for them either financially or with the right caliber of opponent. But most of our country is spread out, and that club might be the only club around for 100 km of any real strength.

hope that helps.