Why do people feed their kids junk food?

It's really disgusting when I see fat parents giving their fat kids junk food 24/7. I think that's abuse. Kids should not be eating 24/7 at mcdonald's and NO kid should be fat. Why don't parents care about their kids' health? I know when my nephew was living with me, I cooked every day and never took him to macdonald's. I would do the same thing when I have kids.