Why is car paint so complicated? It's just paint right? Can someone please explain what makes it so expensive and difficult?

Why is car paint so complicated? It's just paint right? Can someone please explain what makes it so expensive and difficult?

Am I the only one who thinks it's insane that the most expensive paint goes onto a moving vehicle that is most likely to get scratched, dented, or damaged? Ever car paint repair video requires like 20x steps and hours of buffing/polishing/wiping. And shops(MyAuto) charge 15,000. Why can't I just roll on a fresh coat when it needs one?