Euros: Why didn't Americans go to other countries?
Americans: there's only three countries on our entire damned continent, and ours is in the middle. Without needing to fly we have literally two choices. It we could drive for a thousand miles and still be in America.
All of continental Europe is smaller than our country and we mostly all speak the same language, more or less. It's debatable if Louisianans speak English.
Everything south to Panama and the whole Caribbean is part of North America.
Continental Europe is about 10 M km^2 (I subtracted the UK and Iceland for you)
Th US is about 9,5 M km^2
So about the same, which is impressive, but it doesn't hold you captive. You can still go to other countries on holiday.
Also there are a ton of native languages within the US plus settler languages like Tejano and Pennsylvanian Dutch. So if one wanted to have a cultural vacation, it would be possible.
I don't think they're saying they can't, it's just a lot more expensive, time consuming, and requires planning (different currency, sim card, etc). When America has so many landscapes and major cities right within our borders. Many Americans eventually do travel abroad.