Earlier quoted context omitted.
For what it's worth, the US government requires income tax to be paid on foreign earnings, even while living and working overseas. To avoid that, you'd have to also renounce citizenships, which is expensive and at the government's discretion.
EDIT: I was wrong about this, see comments below. False. If you renounce it it's expensive and difficult to get it back, and but renouncing itself is free and unilateral. https://travel.state.gov/content/travel/en/legal-considerati...
https://www.forbes.com/sites/robertwood/2015/10/23/u-s-has-w...
To sum up, there was a $450 renunciation fee as well as a $450 fee for relinquishment, but both were jacked up from $450 to $2,350. This does not include exit taxes and the like, but while $4700 might seem trivial to the well-heeled, it's a far cry from free (and unilateral).