While I don't wander up to people and ask those questions, when my daughter was a curious toddler I would encourage her to ask the questions, in a polite way, that she had.
One day she did have questions, in a Sam's Club, about the way that a family of Muslim's were dressed. The women were wonderful with her. They told her that they kept their hair covered to honor their families and God. That the beauty of their Hair was only for their families and their husband and to show it to others was to take away from the gift that they were giving to those people.
My daughter left knowing that those Scarfs were a demonstration of love and not a denegration of women. She now has several muslim friend (she is 13 and her friends are a few years younger) who attend taekwondo classes with her. These girls wear their scarves all through class, kicking, punching, jumping and rolling on the floor. There is nothing about them that is anything but proud and enabled. My daughter never questions the headwear, she just knows what it is.
Another thing we struggle with that was mentioned before with my daughter is not to "profile" when she tells me about someone in class, or at the store etc and she starts off with "the black kid" I stop her and ask her "how is another way you could have described him to me?", So she can start again and say "There was this kid with a red shirt, and he was running around and..." There are a million ways to single someone out without starting with race. I agree that sometimes the police need it when describing someone who is missing, or committed a crime....but there is no reason a 13yo needs to describe a person that way. There is certainly no reason religion needs to come into it.
Laney