I do not think it is that simple. We are not always talking about under the age of 12, things happen to teens too. The problem is teens have to be allowed to be on their own to a point, otherwise they do not learn to be responsible etc etc.
The only problem I have with background checks is what are the boundaries? What prevents someone from being able to work?
As I have mentioned I can understand the sex offender thing when children are involved but are all convictions going to put a shadow on people i.e. they are capable of being a sex offender because they stole a car or ?