But how can that be done, in practice? Cases like the one that started this thread seem, as far as one can tell, to be based on foolish behaviour by selfish individuals. In the wider picture, though, is there an easy answer to these two problems? .
Firstly, in practice we are talking about (superficial?) appearance. The " if it looks like a duck,. etc". But some people, even if still fully male bodied, are by virtue of build and care taken to merge in not at all easy to spot.
Which means that if there is "calling out " to be done … some genetic female who happens to be a little bigger / less stereotypical in build will get a horrible experience. Not good for the self esteem, that sort of thing.
Cubicles, in future, may become necessary everywhere, maybe? . This would take years, cost a lot, and would not remove the basic issue, just move it to one side a bit.
If we could find a way to tell all "trans" m to fs to get out of the changing rooms unless they have had surgery, and even then be ultra cautious and look for a cubicle, we would.