thefts under stalls make the dividing walls between the cubicles full length. Problem sorted.
being unable to use facilities due to age or disability, use the disabled facilities. Problem sorted.
women who find the wait time for women's facilities too long Well the queues will be considerably shorter and quicker if men aren't in them. Problem sorted.
Women with sons worrying about allowing them into the mens alone Depends entirely upon the age of the son doesn't it? Under 8 and I can't imagine any woman objecting to a little child going in with his mum. Over 8 and you can either stay outside the toilets and watch out for him, or use the disabled or unisex toilets where available. No problem.
women who feel tasks with more childcare fall to them with no changing stations in mens toilets. Baby changing facilities are, in the vast majority, a separate cubicle; neither male nor female. Even in tiny cafes, the signs on the doors are "male" "female" "baby changing" or just "toilet" with baby changing facilities inside. But if fathers with small babies recognise that they should have baby changing facilities too, that's another thing that they should be fighting for.
Luminance we've managed for many, many years to cope with our toilet facilities; queues, children, disabilities et al. What we haven't coped with is men in them. If men want to change their kid's nappies and their aren't the facilities in their toilets, they should start campaigning for them. Why do you have this urge to problem solve for men? They're grown adults who have full capacity and capability to get what they want or need without "the little woman" sweeping up ahead of them to make their lives easier. No wonder men have been so successful in getting women to move over, make room and shut up when some women are so desperate to take over men's own agency for them.