The majority of users are surely from the US, and so questions that don't specify origin but whose answers may be more properly dictated by knowing their origin end up getting answered by the majority US user-base, even though the original person asking the question isn't from the US.
It's fair that people from elsewhere shouldn't always have to specify they're from elsewhere because the entire internet does not exist just in the USA, the USA just has an outsized influence on the internet. I can see how that frustration could arise and why European-based communities would be helpful. It's the same issue on reddit, if you're not on a country-specific-level-sub, the default answers are from US users.
It's genuinely an issue, and I say this as an American, mostly because I'm guilty of it myself. We absolutely dominate the online discourse and usually default to assuming questions that don't specify where they are about must be American. It's a very Amerocentric view of the world and the internet.
+1 for good UK/European communities.