Voyeur banned on that basis but seems unreasonable to me. Wearing a skirt is like undressing in front of a window with no blinds or curtains. Sure it is only visible from a certain angle but not exposed.
Women who wear dresses or hijabs down to the floor would not have to worry about low cams on shoes or umbrellas. Nor would those who wore pants or shorts underneath.
Skirt wearers like the risk. They might trip or wind might blow. Someone else may trip or be ascending stairs behind them. Or be on a lower elevation in a shopping mall where their panties can be seen through grating.
It would seem very simple to have a lower expanse of material blocking the lower portion of skirt. Webbing which breathes yet both obscures panties and prevents the skirt from rising. People who reasonably expected privacy would wear things like that.