I'm referring to the US, though to be honest including Canada wouldn't change much. (Mexico is a whole different story)
I know it's not a common opinion, which is why I made clear that it's just my experience. I've been to 19 US states and 15 European countries and I found Arizona to be more different from Pennsylvania than Romania was compared to let's say Spain or Germany.
I'd say it's probably a matter of not having a 'european palate' so to speak. It's like if you give two red wines to someone who doesn't usually drink wine. They'll tell you they taste the same, but to someone who drinks red wine daily, they are totally different. I have traveled the US, and have lived in Europe for several years, and would completely disagree with your assessment.