The point I mean with the kid working at Starbucks is that most wage earners will have a very simple tax requirements. In many countries they won't even need to send in a tax return since it'll be done automatically. If they are a US citizen on the other hand they will now need to employee a specialist tax accoutant to handle tax requirements from the US and put in their paperwork. All to determine they owe the US nothing.
Ted Cruz was born in Canada. HE was a US citizen at the moment of his birth without having set foot in the US. If his family hadn't moved back to the US then he could have grown up in Canada as a US citizen and he would have had to file US taxes once he started making money. All without ever having set foot in the US.
Just count taxes and countries:
a) you pay taxes to one country only - normal taxation;
b) you pay same taxes to the country BUT you are also paying additional taxes to US - double taxation.
You aren't paying more than if you live inside of the US. The foreign tax credit means you only pay the difference in income tax rates between the US and the foreign country. You don't pay everything you'd owe in the US (say 39% of your income), and then ALSO pay everything you'd owe in the foreign country (say 30% of your income, for a total in 69% of your income, THAT would be double-taxation).
Consider the case where you are earning enough money to be above the thresholds and in a country with higher income taxes than the US. The IRS will say that you owe X in income taxes, but will also give you a tax credit of X+Y based on the taxes you've already paid (assuming a tax treaty). As X+Y>X, you will not owe anything in the US.
Double taxation has a specific meaning and doesn't mean "paying more than one tax".
a) If I pay income tax and e.g. war tax, then this is two taxes. b) If I pay income tax and then earnings tax on top of that, then it is double taxing. c) If I pay income tax to country A, then same tax to country B, then it is double taxing.
We are talking about c).
Wikipedia:
Double taxation is the levying of tax by two or more jurisdictions on the same declared income (in the case of income taxes), asset (in the case of capital taxes), or financial transaction (in the case of sales taxes).
Except they don't. You have an exemption for foreign income.
"It is even possible you have never set foot in the US yet are required to pay uncle sam's taxes."
I don't believe this for a second. You would be a US Citizen, therefore you would have stepped foot in US territory.