There's a lot of kids that aren't like that once they reach, say, toddler age. They know they can terrorize mom/dad as much as they like and they'll still be there, so they ruthlessly exploit that. They can be ruthlessly terrorizing next to their parents, but put them next to a stranger they'll be polite and relatively quiet because they intuitively know they are capable of anything.

i.e. when my child was young, a waiter could hand them a lemonade and they'd be ecstatic. If I handed them the same lemonade, they would start screaming at me the color of cup was wrong.

I can imagine! I'm just speaking of my kid in this current week. By next week she'll be offering us a completely different traveling experience