Up to what age do you feel it's ok to bring a girl into the men's locker room at a pool?

I have seen a lot of women taking there boys and girls into the women's locker room! They take them in together, so how do they separate them once in there! I assume the boy sees a lot of women nude in there! But if a single Dad wants to take his children to the pool for a day of fun, then he is condimmed for doing this! If he takes the boy and girl into the mens locker room! But it's alright for a woman, because society looks at it like, well she gave birth to them! So everyone seems like it is OK! The way things are today I would not send my children into either locker room alone! When I was growing up people looked out for the children wheather they were their children or not, to insure their safety! There wasn't a bunch of crazy people trying to harm children back then as there is now either! We wore our bathing suites under our clothes from home to the pool some times! Then went in the bathroom and dried off took our wet sute off and and put our clothes back on! Put the wet suite in plastic bags, then went home!