Maybe, yeah. But is it neglect on the part of the developer (What are the consequences? You installed the app, no?), on the part of the parent not supervising (I'm kinda defending this position in this thread) or a reason to fix this with a generic law?
I'm not trying to be difficult, I really think that it's the parents' responsibility. And if ads are considered harmful in your household, don't use ad based apps / use an ad blocker? That should solve the problem on a local level.
Edit: It just came to my mind that ad supported apps are often/usually free.. Is that the case here? Because I seriously dislike the idea of blaming a developer of a free application for different ideas about morality or a bad choice ('copy/paste some ad integration code' - stupidity vs malice?) in implementing a way to make some money.