If you're a cute kid, then you can get away with a heck of a lot more than an adult can.
For example, if you're a kid on an airplane, flailing in your seat and crying is pretty much expected. If you're an adult? Well, let's just say it's not going to end well for you.
The same goes for sharing food. Like how weird would it be if me, a 215-lb hairy man was sitting next to Prince Harry, and I just reached into his popcorn box and helped myself? Pretty weird. But if I was this adorable little girl who helped herself to some of his snackage, no one bats an eye.