There are still many parents who are happy when they see that their children like to eat, and they are even happier to serve anything to their children who like to eat.
Happy children are easier to handle, at least in the shortterm, so some parents just give them what they want. For others, it is a convenience thing, where it is easier to give the kids junk and keep them happy, than actually spend time caring enough to provide quality.
Children are subjects that cannot be held accountable.
But, they grow into adults who are held accountable, even though they have been conditioned since childhood to not look after themselves well.