MDD, the way we are leaning in some parts of the Yiddishe velt, there is coming a time when a woman not wearing a burka will be considered as being untzniusdig. There ARE basic laws of tznius, but there are also chumrahs, and there are interpretations of what those laws actually mean. Not everyone is in agreement as to what the loshon refers to. There are discussions about what the shok is (i.e., does it or does it not include the knee), how much sei-ar showing from a married woman’s head is considered to be erva, what type of head covering is mandatory, what is permissible within the Halacha, is red assur, or is any bright color? How tight is too tight? Did women really wear STOCKINGS in the midbar?
Yes, there are basic laws of tznius, but there are also rabbonim who hold different opinions as to with how much latitude within the law, one may interpret those laws. I am not chalilah saying we should be lax, but each generation has had its own interpretation in this area, and it is not as glatt an issue, IMO, as you are presenting.