That's because girls don't mention it to adults. It's just what happens. They get harassed on their way to school by both boys and random men from 20-80 years old and the most they'd get would be 'why were you talking to them? Couldn't you ignore them and walk away?' or 'that's just how men/boys are'.
Then they get into school. 'Why didn't you say anything to the teacher? Why did you let him hug you? What were you doing on the field in the first place? Had you rolled your skirt up? He just likes you. He was just showing off to his friends. Why weren't you with any friends? What were you thinking of sending that photo? Now what is everybody going to think of you?'
and that's if they complain - 90% of the time, the hugging, the nudging, the groping from an unidentified boy, the one they liked but didn't expect to be demanding photos but says they'll just tell everybody she sent anyway, the hanging a schoolbag over the lock to the changing room door, the catcalling from the classroom they have to run past during PE, the showing her explicit porn, the questions about 'do you do anal? Jamie said you did', 'I can see your bra, why are you showing off?' is kept quiet or excused by 'Oh, don't worry, Miss, he's just like that' isn't even anything weird enough to even think of mentioning, much less complaining about.