Doesn't the federal US do the same thing? If an American citizen lives in a low-tax place, US tax applies until that person's tax burden is at least as high as in the US. I'm not going to argue that this is a just thing to do, but if it's legal federally I'd like to know what's going to keep Alabama from doing it.
The special thing about the US federal tax is that it covers everyone the law covers. Most countries tax residents or some other subset, perhaps "residents old enough to work", you get the idea. The difference is the set of people who are subject to US federal law for a reason other than residence. There are things you can do that bring you into scope, including some forms of work.
