Take this with a grain of salt bc small sample size, but I've also heard from South or Latin Americans that simply saying "American" = USA. It's just that rest, I don't know why.

Language might be one reason, and Hollywood and other cultural exports, but also I think people there identify more with like a Global South than as part of the American continent.

So to me it's one of those things that you would think increase welcomingness and inclusivity, but for whatever reason in practice kinda somehow does the opposite (or not opposite, but just has the negative effect of sounding awkward without much of any positive benefit).

But I'd be happy to be proven wrong if that's actually the way it is. If you find out, please let us all know, maybe with a post about it!? :-D