I heard on the news a discussion of this law and while the person was definitely anti-child abuse ... his concern was it would lead to kids thinking that if the plate wasn't green, they didn't have to worry. A bad message.

And, it assumes the only driver of a car with those plates would be the offender. That means that anyone getting behind the wheel (including the offender) could become target (or any passengers they might be carrying) of someone wanting to do harm to all offenders. Might result in killings or attempted killings of possibly innocent people.

I think while the idea is good in it's intentions, maybe more thought needs to be given to the possible complications. Maybe something that'd be required WHEN the offender was using the car without other (adult) passengers on board. Don't know the answer and actuallly liked the idea before I heard some of the arguments against it. Now, I'm not quite as sure if this is the right answer.