@janbb I’ve written about this before, but maybe I’m being too subtle, or just not explaining what I mean.
The problem is not so much that “bad men won’t be deterred by a sign”. We already understand that because of the abject and total failure of “Gun Free Zone” signs. (Don’t worry, I’m not going any further than that sentence on that topic.)
The point is the normalization of men entering rest rooms and locker rooms formerly reserved to women. Right now if I saw a man enter a women’s room I would know “there’s something wrong there; he doesn’t belong in that area”. And while I might not and other onlookers may not physically attempt to stop him we would all know “he’s breaking the norm”. This is something to remember; his face is one to remember; he’s not respecting boundaries properly. That’s a man who bears watching and remembering. We might even warn off other women from entering, and they would take that caution.
As things stand now, “a man” entering a women’s restroom or locker room is already assumed to be ‘bad’ or ‘off’ because of that refusal to obey the societal norm. (Unfortunately, that’s what causes the problems that trans-gendered people now have to deal with; I get that.)
When “anything goes”, then “a man entering a private room with one or more women – or girls” is nothing remarkable. In addition, women would be put in an awkward position because it would seem to be “unseemly” or “prejudiced” of them to refuse to enter or to leave while he was inside.
As noted many times, “the transgendered” are not the problem, I think. It’s those who do bad things under the cover of normalcy.
The other problem that I see, and it’s a much more generalized one, is “What are the numbers?” We seem to be demanding huge changes for what appear to be outliers in society. What is the percentage of people undergoing gender transformation who can’t at least pass as the gender that they want to assume?