There was an article in the Jewish press a few weeks ago.
There was a Kiruv Rav who gave a speech to a mixed religious/ non religious audience and realized many of the FRUM people didnt really belive either.
And he wondered why this was. One of the things he mentioned was Tzniut. Some schools claim some things are Halacha Tzniut, but really are only Chumras. When the girls find out about this, they are not too happy