My DD has always *loved* fairy tales, and does love the idea of princesses. The thing is you don't have to let Disney own it, yk? We read stories about real princesses from all over the world. She likes to dress up in play silks as her "princess" dress. She pretends that her baby brother is a prince.

:
If we go to a play cafe with dress up clothes that are disney princesses, it doesn't matter if she plays with them, to her it is just a beautiful dress. Her friends talk about the different princesses, but that is from another child, yk? Not the disney marketing. Her cousin has some disney dresses and they just dress up and make their own games, and stories.
Honestly, I think you can control how and to what depth the exposure is. If your child watches snow white does that mean you have to buy every princess thing, watch tv, etc? Of course not. You are the parent. You can let it in or not.
She knows that there are 'princess' merchandise, but we just don't buy it. But then we don't really buy toys except for birthday and Christmas...
It also helps to be a TV free home, and her school bans commercial characters as well... so her world isn't really made of princess this and that, except in her imagination. And our school *is* a public school.

(public schools are not this monolithic thing where they're all the same)