US Defaultism is a thing on the internet. I've seen it plenty here to the point of thinking of starting a USDefaultism community just to make fun of it all.
If it actually bothers you to the point of where you're tired of seeing it, I'd recommend blocking (or filtering, depending on your Lemmy client) some US-centric communities or maybe even instances to bring some more balance in your feed.
Yeah, bad phrasing on my part, sorry. To have a laugh with it, would be a more fitting way to put it. Not necessarily at the expense of the person posting or anything.