They aren't. The target for those games are middle aged, "middle class" women. Especially childless women. You just don't realize that the loud sounds and bright colors appeal to another demographic other than children. Usually those games are terrible for (as in the children don't like them) children. Its because those are usually pay to win games and adults can just out-spend them (and the adults are often terrible winners).
Those kids shouldn't even have a mobile device to play said game. That's where the parents can, and should, make a difference: don't let your kid even have a smartphone in the first place.
And the reason we have these ads is that corporations are hoping that the kids will indeed disobey, and whine constantly at their parents, until they have their way (as directed to by the targeted ad). There was a good reason why targeting kids in ads used to be illegal in Europe.
The parents' job is to say no. If they're letting themselves be influenced too, that's bad parenting.