The geographical differences between America and Europe is a legitimate reason, I think, but I think Fame's giving Americans a hard time.

I know a lot of English people who've been to Europe, of course, but the extent of their travels have been package holidays, where they travel to the continent to lie on a beach all day with other English holiday-makers.

It's hardly "Culture with a capital C"; but "travel" as a concept has its own changing fashions. Certain places are "more cultural" than others, etc. There are different kinds of "Tourist" and "tourism".

In short, the apparent insularity of ordinary Americans isn't unique to your country, Fame.

If I ever come into unfathomable amounts of money, I'll travel the UK top to bottom before "seeing the world".