The US government will track US citizens everywhere to get tax money. If you leave to work in another country, you still pay US income taxes. America and North Korea are the only countries that tax you on your worldwide income.

Quelle: Naturally the Feds Want to Raise as Much Money as They Can

Das wäre ja so, als würde mir meine Heimatgemeinde Giffers (FR) jährlich eine Steuerrechnung zusenden.

Nachtrag

Und es wird noch schlimmer:

If you want to give up your citizenship, you have to give up nearly half your wealth above a certain level. The Economist magazine calls it ‚America’s Berlin Wall.‘ […] Once you’re gone, you’re not legally allowed to come back and visit family and friends. Yes, if the government decides you have renounced citizenship for tax purposes, a federal law prohibits you from entering the country ever again.