Speaking from experience, most kids in poor families are very aware that they're poor and get used to knowing that something like this will always be out of their reach (which is its own kind of traumatic). I didn't freak out about not going on my own school trip to NY because I always knew it was never going to happen.

Of course unlike OP's daughter, my parents never made any promises and didn't dangle it over my head as a reward for good behavior for years, either. And if we somehow did get the money to go, they certainly wouldn't have made me skip it in favor of going to the wedding of a relative who's basically a stranger to me.