Well, if you narrow that to "modern music that's played in bars in places in the US without significant ethnic content" I'd say you're right.
There's a whole population of folks here in Texas that enthusiasticallly listen to, dance to, and patronize establishments that feature music from Northern Mexico and southern Texas, featuring double bass, tuba, accordions of several types, and a number of other features.
Cuba has entire genres of music people spend their lives working on and never exhaust the material. Brazil ditto. These aren't "guitar/bass/drums/vocals". Then there are fiddle tunes - Cape Breton, Texas long bow, Cajun, etc., etc., etc., etc., I don't even know how many variants there are, and that's just in North America. Klezmer certainly isn't "guitar/bass/drums/vocals".
Ever hear of the Turtle Island String Quartet? Either/Orchestra? How about that album Gil Evans did of Jimi Hendrix tunes?
I'm serious, I think you need to do something like go to Wikipedia and get a general list of "styles of music" and start listening.
As an example, I always thought I would LOVE Irish music. Hey, I'm a flute player, I'm Irish in heritage, this will be right up my alley. Well, I found out I really don't care for it much, certainly not enough to ever get involved in playing it. On the other hand, I figured bluegrass was just some more of that hick stuff, then I got involved and found out I love playing bluegrass. Set your preconceived notions aside, get a playlist, and start listening. Not to the same stuff you've been playing and burned out on; DIFFERENT stuff. You might find Conjunto button accordion is the thing you REALLY want to do.