Some people don't know and some people don't want to know.
I'll never forget when I lived on E North Broadway right by Cleveland and I would shop at that kroger right there. I used to wonder why poor people were so fat. Then you take a quick look in their grocery carts and the answer is clear. White bread, twinkies, bologna, hot dogs, 400 frozen tv "dinners", kraft singles, etc. No fresh produce, no boneless skinless chicken breasts...
Then once when my wife and I were shopping, there was this lady that I kid you not, was the size of that mom off honey boo boo, and her two teenage daughters that were much smaller and one of the duahgters picks up a family size pack of ho ho's. the mom goes, "Put that back and get the smaller box, we don't need the family size." And My wife and I look at each other and think, "YOU DON"T NEED ANY SIZE! What the heck is wrong with you?"
I like to think if I am ever on government assistance, I would utilize those resources to buy healthier food. Better quality food, and train your body to control portions.
This is not me hating on poor people, we were poor when I was a kid. It just seems like, again, lack of education either because knowledge has not yet reached them, or they don't want to know.