Is that what these parents did Brit? It seems to me that they were vigilant. They recognized something was wrong with their child and they did what they could to catch the maid, and then they reported her.
If there were no previous complaints about the maid, how would they be able to know she was a pedophile?
All this law does is alert people that should they catch their nanny abusing their child they shouldn't turn the nanny in. Which means that nanny can go on to be hired by another family and abuse their poor children.
Blaming the parents for this is scape-goating to the extreme!