To wonder why do few girls have short hair nowadays

[Chewystick]

That’s it really. When I was at high school (80s), half the girls had short hair. However, I can only think of one girl my DDs (who have long hair) have known through school who had short hair and she has long hair now. When did short hair fall out of favour?

It's not a universal symbol of femininity

I agree. I was wondering more where the stereotype initially came from and when, how this has been perpetuated and where it has either not appeared or been deliberately challenged.