>There's also the notoriously difficult hassle of complying

I would've thought that the hassle came when the American switched to a non-American employer or ran a business outside the US. I would've thought that if the American is getting all his or her income from an American employer the hassle could be mostly avoided (even if he or she is residing outside the US) especially if the American is merely continuing to work a job he or she had while living in the US.

But maybe I am wrong.