>>Why would it be acceptable for an Estonia, Ukraine, Caledonia, Scotland, or Quebec to leave their unions, but not, say, a Delaware?<<
They are not part of the USA and governed by the USC AND they continue to operate as countries, just countries that have pledged fealty to an Emperor.
When a territory joins the US it says “this is now a State.” No more, no less than any other and the history becomes legally irrelevant. A country that joins the EU continues to be a country, it just promises to adhere to a bunch of rules and regulations shared by other countries.
“When a territory joins the US it says ‘this is now a State.’ No more, no less than any other and the history becomes legally irrelevant.”
In the ratifying conventions, do you think the majority of those who voted believed that?
Would you personally have voted to join?