Why Offer?

So, why *do* they offer children's ticket prices for R-rated movies? I mean, if you're of an age where you qualify for the children's discount, you're not supposed to be watching an R-rated movie. Hell, they probably shouldn't even offer them for PG-13 movies. And, maybe if they didn't offer children's rates on those titles, parents would be less likely to bring toddlers to the midnight showing of the latest splatter flick.