We know that women pose a far lesser risk of sex crimes than men. So I cannot imagine there are a wealth of women taking photographs of children's genitals.
And I imagine men equally aren't caught doing that; I'm not sure why 'trust' would make one oblivious to a woman taking photographs of a child's genitals in a nursery. I would think it far more likely that men (and a small percentage of women) are taking them unseen, in the few moments they're alone while changing a nappy, as does happen with workers of both sexes in busy nurseries.
Besides, as I said, one man raped at least 12 children and put semen in the food of hundreds of others before he was caught, so what's your point, exactly?
Not to mention, while both are terrible, photographs alone are not as bad as penetratively raping a 5 month old (something I shouldn't have to point out).
As I believe I said, however, my children didn't go to nursery. They went to kindergarten, accompanied by me, and otherwise were always in my care or my husband's care, while young.