It's too bad there isn't a Parent Product for each commercial product in those sections. The Parent Product is based on negative reinforcement through a bad experience. Buy a certain ice cream brand, it tastes like crap and gives you a stomach ache. Buy a certain candy and it tastes terrible and puts you in the bathroom. You could switch that product with something a child wants badly and is giving you a hard time for.
So, you'd be at the store and the child wants Mr. Big's Ice Cream Goofballs because they've been advertising like crazy and all their friends have them and it's the greatest thing on Earth. Fine. Go ahead and buy a box but in this case, it's the Parental Control Product.
The kid goes home happy, tears open the box and BOOM! Bad aftertaste, negative effects, etc. And the parent gloats and says, "I told you so!" and the kid sullenly agrees. The next time at the store the behavior is changed and fewer arguments happen.