These threads are frequently frustrating, because over and over again people talk about it as if it's girls v boys and ignore the fact that this is a problem for adult women, because it's mothers who have to send their differently-sexed children into the men's toilets, changing rooms etc.
Obviously the answer is not to just bring them into the girls' ones, but that still leaves the problem unsolved for those mothers, who, remember are women. It has to be OK for us to ask this as a question and brainstorm solutions without people making out that we're somehow helping the enemy in worrying about male children.
Men do not have this problem, as when they are out with their opposite-sexed children, the toilets they are sending their children into alone are the ladies toilets, which are relatively safer.
The idea of redesigning men's toilets is interesting and is one of the few new ideas I've seen. It is nice to see that this thread has been slightly different in not just being over and over again people arguing that it's somehow not women's problem, when it is, in fact, precisely a problem for women, because it's mothers out and about with sons who face this issue frequently.
It doesn't do me any good as a parent to shrug my shoulders when I'm out and about and say "about time men stepped up to solve this problem" (as if, ludicrously, all boy children belong to men and all girl children to women) - in the moment, when I'm out with sons of a certain age, it's a problem for me, a woman. Discussing possible solutions is a legitimate use of time for women and feminists in particular.