Since you weren’t there, I think you’re being presumptuous in assuming that the mother of the little girl was packing it up and calling it quits to teach her child that her bad behavior has consequences. It sounds like the mother was offended by her friend’s behavior in calling out her bratty kid, which she had every right to do. The kid probably had a meltdown because she’s not used to being called out by an adult. Obnoxious kids whose parents set no boundaries grow into entitled adults, who never having heard the word no, are astonished when the world they now have to adult in does not tolerate or reward them.