Presumably they have requested permission from the owners of the property to hang these signs.
It might be more effective to have these guidelines (along with the reminders about shorter shaitels, looser clothing, less precarious heels, etc.) printed on mirrors, which should be hung in the hallways of shuls, schools, bathrooms, dressing rooms or wherever women would be likely to look at them. (Since we women often check our reflections in store windows, maybe caring proprietors would be willing to have these guidelines printed directly on their windows?)