Getting off to images of child abuse (simulated or not) is a deep violation of social mores. This itself does indeed constitute a type of crime, and the victim is taken to be society itself. If it seems unjust, it's because you have a narrow view of the justice system and what its job actually is (hint: it's not about exacting controlled vengeance)

It may shock you to learn that bigamy and sky-burials are also quite illegal.