I did my entire schooling at an all girls school, where we learned such important things like cooking, sewing, child-rearing, Latin, ballet, ballroom dancing, elocution, and my personal favourite- table setting classes. Math ended in year 9 because it was "too hard for girls" and we never had science. We had history and geography, but it was very basic.
I can set you a really nice table with my education.
That was the 70s-80s though and of course that type of fluffing around is not acceptable schooling nowadays. However, I would be concerned about what was on offer, using a more recent example, my 18yr old's girlfriend attended an all girl's high school and she did tell me once that what she hated about her school was that they had all these classes on offer but they needed a minimum number of students who wanted to take it to run them. It meant that she missed out on Information Technology because only 3 girls wanted to take it, when the class minimum was 8, but there were 4 Fashion Design classes running at once. Her school also didn't offer Specialist Mathematics (the highest mathematics class) because for a decade no one chose it, meaning no student at her school can apply to study Medicine at University.
I think about my kids, mainly DS18 and DD13 and in single sex schooling I can see how the same would happen to them. DS was the only male in his Classical Studies (ancient literature, basically, I don't get the funny name) class, and one of two males in Literature. DD is in an accelerated science program at her school with 3 girls and 13 boys, and it's no secret how underrepresented females are in STEM subjects.
I simply wouldn't put them in single sex schooling because their options would end up being limited. I don't see what gender equality has to do with single sex schooling, if anything one could argue that the prevalence of non-STEM subjects in all girls schools and the lack of humanities subjects in all boys schools is anti-equality.
