Most Americans have never been outside their country and have a limited media created stereotypical view of the world that is laughable to the rest of us.
They'll believe anything the media or government tells them 'cause they simply don't know any better.
Ummm.... What?
America is large place. Think of it as an island... a very large island, at that. Employers here are not legally obliged to offer vacation, though most offer at least a week's paid vacation each year.
Think about that. One week's vacation makes it hard to plan an overseas trip. When I was in the Army, I could take up 60 days per year, and for my current job, up to 30 days, so I'm luckier than most.
Flying out is also expensive. A trip to Paris from St. Louis, for example. Can be prohibitive for people here. It's different in Europe where I can fly to Berlin from Paris and be walking down the Champs in a couple hours.
As far as believing what the media says? A recent poll stated that trust in much of the legacy Media outlets here in the States is at an all time low. Trump's campaign was able to capitalize on that with the last election being as much referendum on our legacy media as it was the Democratic party.
As far Americans not wanting to talk to someone from France? My grandfather despised French people, as he felt they were ungrateful. I don't share that view. I think it might simply be the original posters age, or the fact that Americans they are writing to simply want pen-pals that are not from France.