There is no such thing as "being assigned a gender at birth." Even the nonsensical language of "assigned male at birth" affirms this. Male is a biological sex, not a gender. As is female. We categorise every single sexually dimorphic species on Earth this way. Even the parts of some plants in fact.
Sex is not assigned it's observed. And it's done trivially easily in 99.98% of cases. As I pointed out last time we spoke, most children can make the distinction by the time they're three months old.
And gender is not assigned at all. There is nothing a doctor does at birth that forces a male or female child to conform to gender stereotypes. There is societal pressure on that child to conform of course. We might even agree that this should change (and is changing). But to pretend that anybody is "assigned" a gender at birth is asinine.
And yes, there are plenty of arguments I can make that it's appropriate to question someone's gender identity. You just won't accept any of them because you don't give a shit about women's safety, comfort or boundaries. But if there was a man standing in a women's changing room, or worse, a changing room with young girls, I think it's WHOLLY F**KING APPROPRIATE to question him. So would any decent, responsible human being.
And yes, you can ask why sexual predation is possible (I guess I'd start with the fact that some extremely creepy men don't give a shit about women's safety, comfort or boundaries and sadly we can't keep an eye on all of them all of the time), but that doesn't help address the fact that it is. If you have an idea that will make it impossible, fantastic! Let's talk! As soon as your genius solution is implemented, as soon as it's no longer possible for men to rape or assault women (or just be creepy and make them uncomfortable), I'll fully support the abolition of single sex spaces.
However, if you think that solution is to "decriminalise all drugs," I think you need to take less drugs.
Lastly, as I've already explained ad nauseam to you, the laws aren't aimed at restricting trans folks. They never were. They are aimed at keeping males out of female spaces. This isn't some new thing. Societies and cultures all over the world have acknowledged the need to segregate males and females in certain situations for thousands of years.
And as I've also said, societies change. The point I'm making isn't that trans women shouldn't ever be accepted in female spaces, I'm saying that there needs to be a method of defining "woman" that doesn't allow me (and especially you) to become one simply by saying so.