Yes, those foods aren't good to eat long term. And they're in no way affordable.
Maybe people are imagining they'll live off what's in their larder instead. Except after a few years of poverty, they won't have anything in their larder.
After a few years of this, I start feeling panicky and guilty every single time I have to buy food. A friend of mine took me to Costco recently because they thought it would be a nice trip out for us. I got so overwhelmed by the huge piles of food that I got shaky, burst into tears and had to leave.
That's reality. That's what the apparent privilege of being disabled and on benefits looks like.