I've heard it called "US Defaultism" where most Americans online seem to assume that everyone they interact with is from their country and all US news is considered significant even when it really isn't.
I’ve been guilty of that- commenting before checking what community the post was in. Thankfully, I’ve found that most people outside of the US prefer gentle correction. Unfortunately, I doubt the average person from the US would show the same courtesy if the roles were reversed.
I find that it correlates more with education status than nationality... but therefore it surely is more rare among the set of average Americans who have access to the internet than globally.