It IS up to the parents, and I guarantee you that most here who are in shock over this do NOT have teenaged daughters and are equally clueless as to the "culture" in high schools these days.
Folks, if you're over 30 (if you're over 45 like me, fuhgedaboutit), know that "this ain't your daddy's high school" any more.
My high school aged daughter wouldn't be caught dead outside this house dressed like that. I wouldn't allow it, her mother sure as HELL wouldn't allow it, and thank God (literally) that she's a great kid with her head on straight and wouldn't even consider it. She doesn't dress like a nun, mind you, and frankly, she looks great in whatever she wears. Modest-yet-fashionable clothing is her order of the day, and she's very, very up on fashion (and will pursue a career in the field). She and her friends are constantly sneering about these "hoochie chicks" at school. They dress provocatively but wind up looking ridiculous.............and the idiot of a principal allows it if the girls are a)juniors or seniors and b) cute enough.
THAT'S a small taste of what it's like in a new, very upscale neighborhood's high school in today's America.
Thank you, that was the point I was trying to make, you just made it better and more understandable. Having had sons and not daughters, I am thankful to you for showing how girls with self respect, like your daughter and her friends, feel and talk about those who dress as if they should be wearing a sign saying "Come and get it, $5.00."
Alas