Earlier quoted context omitted.
The US is one of very few countries who collect income tax from their overseas citizens.
There are only two; the US and Eritrea.
https://en.wikipedia.org/wiki/International_taxation#Individ...
As a side note, the biggest difference seems to be how countries treat foreign income.
Almost every country that has Income Taxes will tax any local income.
But there's a lot of variance on what they do for foreign income.