The industry became regulated because hair stylists used chemicals that did a lot of damage to their customers. I remember it in the fifties or sxties.
It was very bad at the time.
But is that still the case? I get my hair highlighted and colored, but I don’t think it’s too damaging. Yes, I suppose that it could be - someone forgets to set the timer, and my hair is destroyed, but can regulation prevent all of that?