It's just a phase kids have, it's called the "bratty phase"
Yup. It's tied to an almost instinctual drive for independence. It's an evolutionary thing.
Those who lack it are the ones who end up NEETs for life. The expression of that tendency has gone up over time thanks to the fact that lacking an independence drive is no longer something that will get you naturally selected out of the gene pool.
Bratty, defiant children are just genetically superior.