If an adult pushes into line in front of your child, that is wrong.
If an adult is in line to meet the character there is nothing wrong with that. Even if the adult is standing in front of your child. Even if, after the adult has their turn, the line is cut off so the character can take a break.
At Ollivander's, the WANDMAKER does the choosing. He is the one you have an issue with if he chooses an adult, not the adult. Obviously it is not a requirement of the wandmaker's job to always choose a child. Unless you are advocating that an adult who is chosen should stand aside and ask that a child be chosen.
Sorry, but Orlando theme parks are not the exclusive property of children.
I'd wear that on a shirt.