There are different levels of tznius, and also there are different ways people interpret the concept. I know some incredibly tzniusdig young ladies who wear skirts that are slightly shorter than most of us would think of as being so. You would never hear L”H from their lips, or see them behave in a way that is immodest. I have conversely seen girls with skirts several inches below the knees, collars up to their chins, sleeves down to the wrists, whose personaly sense of propriety is very unladylike and in my opinion not tzniusdig. Forty years ago, frum girls who were considered to be modest, wore shorter skirts than even today. They wore pants, they wore shorts with sleeveless shirts, they wore bathing suits and went mixed swimming.
They were yeshivah girls, they were respectful to their elders, they did chessed for others, they were not loud or ostentatious. But by today’s measure, they would not be considered by many people in the CR to have been tzniusdig, and yet internally they were extremely so.
Yes, we have certain hashkafic absolutes, but we also have to remember that tznius is not only measured in inches. It is measured in actions. Maybe some of the girls who were described, do not fit the mold that some would like. That does not automatically make them untzniusdig, even if their mode of dress might be considered that way by many.