One of the problems is that girls don’t realize that tznius is a bein adam l’chaveiro issue and that they are being cruel to men when they dress untzniusly.
Many of the girls who dress untzniusly are davka very nice people who would never dream of hurting someone else. If they were made aware of the fact that it’s not nice to dress untzniusly, I think they would stop.
Often it is presented to the girls as something they have to do for men. But the way it is presented sometimes turns them off, and their reaction is, “Why do I have to dress a certain way because men have a problem?” Which is a ridiculous reaction because men didn’t choose to “have a problem”, and it’s not actually a problem since Hashem created the world that way for a reason and it is the way it is supposed to be. However, if it is not explained correctly, that is the reaction.
I once discussed it with a student who was having the above issue. When I explained it in terms of “bein adam l’chaveiro” and how it’s being mean to men to dress untzniusly (since you are causing them to go to geninnom which is not very nice), she was mekabel.
But it was clearly a big chiddush to her as it had apparently never been presented to her that way before (she was not from a very Frum background and was attending a modern modern orthodox seminary, so I don’t know if this would be as true for someone from a different background, but I think there would still be some truth to it)