That's a lot of justification for what ultimately just amounts to ignorance of the outside world.

It's certainly not the case that "most adults in the US grew up and were educated at a time..." The EU exceeded $3 trillion in GDP by 1980. The original EU countries included Germany, France, and Italy, so were hardly insignificant.

You don't seem aware that the "EU", in 1980, didn't exist, nor did you do the sums on the ages of the population in school by the time it did exist to realize that yes, by typical textbook replacement timelines in schools, something like the existence of the EU is unlikely to have been in the textbooks during the school days of most people over the age of 30.