The WHU. (That's the World Hairdressers' Union.)
When I was young we all had haircuts every two weeks. It was considered untidy to allow the hair to grow long on the back of your neck. Then along came Ringo and Paul and John and George and we got back to the way our ancestors wore their hair. Barbershops closed down in droves and there was massive unemployment in the barbering business. (They'd long lost their healing creds to the various medical associations.)
With women it was different. Promote long hair, alternate that with fashionably shorter hair from time to time, and women's hairdressers continued to rake in the money.
It's an industry promotion.