Three centuries together is a long time. Many familial, workplace and friendly bonds tie the countries to one another. Also, as long as the territory is vaguely

Three centuries together is a long time. Many familial, workplace and friendly bonds tie the countries to one another. Also, as long as the territory is vaguely yours, even in a confederation, it is at least neutral or mildly positive towards you. Not hostile. If everything was about net money transfers, then the US could get rid of at least 15 constituent states, but half of those would be immediately courted by China, eh?