Sorry if I'm misreading Bender, but do you mean you can't believe there is not a law in place that covers witnessing a child being sexually abused? As it stands there is not. So someone can literally watch it happen and turn a blind eye. More so if they do choose to, in some cases, risk their career to tell the police they have zero protection by law. Almost all other countries worldwide have some form of this law, we don't.
Here is an explanation from Mandate now website: "If you work with children, and see one of your charges being sexually abused or even raped, you might think you and your employer had a legal obligation to report it to the authorities. Not so. There is no legal requirement on anyone working with minors in England (Wales or Scotland) to report such incidents and concerns to the Local Authority Designated Officer (LADO), children’s services or in the event of a ‘known’ crime, the police."