[ceras]

There are people who come at a young enough age, e.g. as infants, and don't know anything at all about their "home" country. They may not even know the language very well, if at all. They likely don't have a single memory of the place.

So while technically you're right - as adults they have a say - it's asking quite a lot. Very few people would move to a (likely much poorer) country with no social support, and likely with no money, just because of a decision their parents made. For all intents and purposes their home is the US, and their identity is American.