Because Metropolitan France (note the capitalization) is how the European portion of France is referred to: compare with Overseas France, which includes territories in South America and Oceania, to be non-exhaustive.
This is a difference in attitude between Americans and French when describing their countries: the French tend to regard overseas territories as more vitally part of their country than Americans do. Not sure why, possibly it was a deliberately-cultivated attitude by the government at some point, or maybe the difference arose organically. Meanwhile I think a lot of Americans kinda-unconsiously barely even consider Hawaii and Alaska really parts of America, let alone the numerous non-state territories.
Actually, now that I think about it, the sense of "Metropolitan France" is very similar to the term "the continental United States"
American here, I’d disagree about Hawaii and Alaska but agree about the non-state territories. The non-state territories being unable to vote and not having representation in the legislature means that they don’t get as much attention in national politics, so they’re less top of mind. (Yes, both of those situations suck and I wish we would change them.)
The restrictions are tied to geography not persons.
A Puerto Rican in California is entitled to all the benefits of US Citizenship whereas a Californian in Puerto Rico is not. Mostly these are related to welfare and elections. This would be the case for the Californian or Puerto Rican living anywhere in the world outside the US.
You retain voting rights of the last jurisdiction you lived in within the US (states or territories) after moving abroad.
So a Californian that moves to, say, Germany can still vote by mail as though they were in California.
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You're mostly correct about the loss of welfare benefits, though. The only exception being that you do remain eligible for Social Security retirement, although some people may not consider that "welfare".
It's remarkable that you said all of this, I'll be generous and say that someone else completely made up the part about the Jones Act and you just heard them and repeated it.
So a regular (ie mainland) US citizen has to file taxes (& pay if earnings 108k+) of living anywhere in world. Does this stay true if same citizen lives in these territories you refered?
> This is a difference in attitude between Americans and French when describing their countries
I'm not sure that's true - it appears to involve a legal distinction. I see many references to Algeria having been an "integral part of France" where other French territory wasn't. But I don't actually know what the terminology means. Anyway, I'd begin by looking to the legal status France tended to give to overseas territories, rather than the attitudes of the French, to explain this.
> Meanwhile I think a lot of Americans kinda-unconsiously barely even consider Hawaii and Alaska really parts of America, let alone the numerous non-state territories.
And this is a perfect case in point; Americans do consider Hawaii and Alaska to be really parts of America, because they have the legal status.
What there is, is a blindspot about territories. Just look at the flag: that there are parts of the United States which aren't States kinda doesn't compute.