It’s not even just Americans who do it. I’ve frequently been yelled at online about what is happening in the Untied States with people saying things like “your president” and “your government”. Since they word it in a way that implies it isn’t their government, they’re presumably not American. I’ve seen other non-americans yelled at in the same way by other non-americans. And no, it’s not fair for them to assume I’m American because I’m talking about American issues, because they themselves are also non-americans in conversations about American issues.
My favourite example is last summer when I expressed my sorrow about merchandise being sold for Aligator Alcatraz by saying “humanity has failed”. Someone responded with “no, you failed, don’t lump the rest of us in with your fuckup” and proceeded to have a long rant about how my country has failed and they will avoid my country so they’re not supporting nazis or risking the nazis getting them. So it’s pretty clear they weren’t American, why were they assuming I was? If you’re a non-american participating in discussion about American politics, why do you assume everyone else is American?
I even saw a post on a Canadian community about how experts are saying the Untied States are dangerous to travel to or something like that, and a bunch of commenters assumed it was American experts and were indignant that the Americans were telling us this. I wish I could remember enough to find the post cause I’m struggling to remember why they were indignant but I remember they jumped to the assumption that Americans were telling Canadians something and it was actually Canadians