As a parent I don't let my children watch things I disagree with. They can probably count the number of food ads they've seen in 1 hand because I don't let them watch TV. They can watch shows and movies but they're either streamed or checked out of the library.
But that's the way I choose to parent my child. If another parent wants their children to watch TV and be exposed to those ads then they should have every right. I'm not going to make a moral decision for them and I don't think the government should either.
I'm the same. My children are practically never exposed to these ads. But, all their peers are.
My kids have never had any fast food, and have never seen an ad, but they talk about KFC and McDonald's constantly. It all comes from their friends at school.
What about the (large, I would argue) slice of parents who want to let their kids watch TV but don't want them bombarded with ads for sugar-saturated foods?
(I mean, we're on HN, so the obvious answer is watching things on a laptop / projector with Firefox + uBlock Origin, but y'know - everyone else).