Ok grand- I hear you. You’re taking the term very literal.
I’m not sure how others do it, but yes, in our family the Mechitzas never come down. Never.
(Only by Mitzvah Tantz)
But I still wouldn’t judge others like you do. I would be them Dan Lkaf ZChus that they (hopefully) got some Heter.
And believe me, I don’t either understand how mixed dancing can ever be allowed, but who am I to judge?
In the next world, we each have to give a Din Vcheshbon, and until then, every Yid is free to follow the Torah in whichever way they understand is right.