Restroom. You're from the US. That explains a lot. We don't call them that over here. You are presumably also very young and don't remember how things were before the gender madness took hold. In the not very distant past a man entering a woman's lavatory or changing room would have stood out like a sore thumb and anybody seeing this would have raised the alarm. 'Good men stay out so bad men stand out' sums it up. This had a deterrent effect. Nowadays it doesn't because all the man has to do is to say 'I identify as a woman' and he has a free pass in many places. Women know if they complain they might end up being called bigots, publicly humiliated and getting into trouble with the law and/or their employer, professional body, gym, club etc, so a great many decide to keep stum. Girls faced with the prospect of having to use all-gender WCs at school just don't go to the loo or stay at home. Religious women who no longer have single-sex facilities to use as required by their religion are excluded further from society. Women and girls who've experienced sexual abuse are also self-excluding from these mixed sex spaces and services.
And let's not forget that this isn't all about physical and psychological safety. There's also privacy and decency. Women and girls don't want males around when they are vulnerable from being in a state of undress. Men and boys don't want females around in similar circumstances.