I don't think this law is meant to prevent parents from abusing their children....but it is meant to simply be a license/background check on those people who systematically "work with" children.
I had a study with an elder's family, privately, without my parents being present. My dad wasn't a JW at that time, and this elder had instructions to "take me under his wing" if you may. While nothing funny went on, the mere fact is that he "worked with children" and that this arrangement of taking a youth from a religiously divided household into a private bible study should be enough to trigger the "working with children" background check. I have since found out that this is a common arrangment with interested youth.
Again, all this is is a background check, and then if the licensee should commit a future act, the State can monitor and let the current empoyer know and/or pull the license. It prevents wierdos from working with children.
I believe there are other instances where JWs "work with" children. Think of just the mere act of going door to door. A child could be home alone and come in direct contact with "2" witnesses. The intent is to start a bilbe study (alone), with one witness in attendance with a child. Further, even if a bible study isn't started, the 2 witnesses have learned a wealth of information about the house (who lives there, are they alone, is there an alarm, doors locked, vicious dog, etc.). Either witness could use this to his advantage. With so many latch-key kids these days, I'd think the Watchtower would want to assure the public at large that their members have passed this State-mandated background check.
Then, there's the building arrangment where JW youth are alone with other JWs (elders and baptised ministers of Jehovah) building a building. That's within the law. If you were a manager of a McD's and hired youth to work with, you'd have to have the license. Sure, everything might be 'out in the open' for 95% of the time, but there are times when a child is going to be alone with a JW in this work environment.
Why is the Watch Tower adamantly refusing to follow this law? What are they trying to hide? Even the Catholic Church has procured licenses for its clergy, why is the Watch Tower totally ignoring the issue (i.e. not even dragging its feet)? That's the million dollar question. The milion dollar answer lies with the fact that there are many child molestors within the Watch Tower.... Saving the facade of Jehovah's religion is more important then protecting Jesus's children.