The police run the same stings to identify and prosecute these creeps and they do get convictions even though no children were involved.
That said, there is something wrong IMHO, with NBC doing the same thing just for ratings.
As a general rule, I think that the cops don't have a financial incentive for success. Sure, they may confiscate the perp's vehicle or computer, but it's not like there's a direct financial relation to the arresting officer.
NBC is in it for the money. Pure and simple. Makes me question their motives.