I get an eyeroll from my friends when the subject of hair length in women's sports comes up, one of my hobby-horses!
I maintain that 'a personal preference for long hair' cannot explain why, out of two squads of players in women's football, not one single one has short hair.
I suspect there is some kind of influence - subtle, subconscious or explicit from sponsors, I don't know - for sportswomen to look 'feminine'.
Hence more ponytails at a women's football match than at a gymkhana...
Little boys and girls with short hair do tend to look pretty much the same in sports kits, and as PPs have said, this wouldn't be problematic if eligibility rules were 100% respected.
There's a post on another thread - a mother asking for recommendations for make-up lessons for her 15 year old daughter... I didn't respond because I couldn't trust myself not to lose it a bit, and I don't want to be rude or confrontative.
But it's 2025, and 15-year-old girls are being coached in how to look more conventionally 'feminine', and older than they are. By their mothers. And girls with short hair are assumed to be boys.😦