For certain categories, the adult is definitely the customer. For toys aimed at children under three, the ads regularly talk about training hand-eye coordinatio

For certain categories, the adult is definitely the customer. For toys aimed at children under three, the ads regularly talk about training hand-eye coordination and other basic skills. For other categories, you could argue that the toy companies are selling a service: Make the kids stop complaining for a few hours. Naturally, an easy way to do this is to be the reason that the kids are complaining in the first place.