“If she thought there was a heter to do what she does now she would uncover even more!”
Why do you say that? Isn’t that a bit harsh?
Girls don’t violate tznius on a whim, or because it looks fun- they want to look pretty, and that’s how they think they can do it. Misguided, maybe, but I highly doubt this girl is malicious in her dressing (wow, that sounded weird).