The problem is when you start looking at universal designs you find that they aren’t popular. People may campaign for them but women won’t use them if they have a choice. They are dirtier, smellier, and not as safe.
Document T (English building regs) has got that right. Single sex provision first, then once that is satisfied, universal designs if room (exception if only space for one loo etc).
Women's toilet provision should not be reduced for increasing unisex provision.