Junior HIgh School hair rules for graduation

In my children's elementary school there were no rules about hair when it came to graduation. Same when they were at kindergarten. However, in Junior High School, there are rules. I don't understand why hair is such a thing at Japanese schools. It is perfectly acceptable for a school to ban children from “getting their hair permed, colored, bleached or braided with extensions". 

However, some rules have been relaxed. For example, when my older Irish friends in Japan had children going through school, some of their children had to dye their natural blond or brown hair black to match everyone else. Isn't that just ridiculous? A lawsuit in Osaka in 2021 highlighted, if you'll pardon the pun, the perils of forcing children to dye their natural hair and the compensation the school was forced to pay will surely deter other schools from continuing that archaic rule. They still enforce a ban on coloring hair from black to anything else though, but they don't make students with natural hair that isn't black to dye it black anymore.

But there are still rules. More in some schools than others. For example, my children's junior high school does not allow children perm or color their hair. But they do allow things like mohawks for boys. But one rule they still enforce that I really don't understand in this day and age, is that hair longer than shoulder length must be tied up in a ponytail. I would like to see the school's relax hair rules further.