I wonder how many "Americans" who travel abroad learn the other
languages (fluently) of the countries they reside in for anywhere from
a few weeks to a few years?

Sounds like a bad case of intolerence to me. These people are trying
to eat and feed their families. My wife's ancestors came from Poland.
They never lost their accents till they died. They never learned
fluent English, but they got by. The kids learned "American" English,
which is often not that great anyway.

Stretch