Yeah, I think it's pretty common for Americans to believe anyone else who can type english is probably also living in America.

"Americans", you mean Cubans? Equadorians?

Really, you do not seem to be aware of the fact that or people leave in either Nothern or Southern amercian continent, and many of them do not speak English.

Each time any US citizen calls US citizens "Americans" it hurts the heart of hundreds of millions of people.

Shit.

I guess it's still not a bad heuristic for them in 80% of cases, so this attitude prevails. HN, however, is quite multinational, so one has to watch out ;).

It is not a matter of "heuristic", it is a matter of basic respect you have for other people living in other places.