I may open up a huge can of worms here, but I am going to respond anyway.
Speaking from the point of view that Ben has (we seem to share a lot of the same views in regard to government), I don't believe that we need anymore "Nanny State" laws either. People have long been capable of taking care of themselves, and just because you outlaw something doesn't mean it still won't happen on occasion. It's just another way to collect revenue, just line every other fine based law out there. Has it stopped or significantly cut down on the problem? In most cases, the answer is no. We have this inherent belief amongst ourselves that we always seem to know what is best for other people, and often times, we seem to think that people as a collective are inherently ignorant, and I'm not sure that is a good way to think about our fellow man.
That being said, I do agree with the premise of the law. A school zone is in fact government property (along with state and federally maintained highways), which they are responsible for the upkeep and safety of. If you were to hit a child in a school zone, yes, you would be criminally negligent, but, with today's "sue everyone and ask questions later" philosophy, I might be inclined to think that this might be a preemptive move to mitigate some civil risk in the matter as well. After all, the government puts crosswalks in that guarantee our children are safe to cross, so what happens when they can't meet that guarantee?
I have no problem with this law, because if you want to get down to a crude, brass tacks comparison here, a "school zone", or the road and highway network is part of the government's house, and I'd abide by those rules just as I would expect someone to abide by the rules of my house. When I turn into my driveway, or private property, the "nanny state" laws should go right out the window