It is not cheap to eat well.
White flour is cheap. Whole wheat or rye flour is expensive. Milk is expensive. Meat is expensive. Real cheese is expensive. Fresh or frozen veggies are expensive. Potatoes are a lot more expensive than they used to be. Two years ago I could buy a 10# bag of potatoes for 1.99 now it is 3.49 for a 5 lb bag. Even white rice has more than doubled in price in two years.
But I can get a 40 count bag of pizza rolls for 1.99 or three boxes of mac and cheese or 6 packages of ramen noodle for 0.00.
Mac and cheese and ramen noodle are 0.99 not 0.00, sorry for the typo.
For $19.90 of staple foods you could easily make more than 400 pizza rolls worth of food, and it would be much more nutritious.
Eating bad is easy and convenient, but it is NOT cheaper.
Economically it makes no sense to say that the staple crops that went into the highly processed premade and often precooked food become less expensive when put into a brightly colored and highly advertised box.
For economic reasons I wanted to reduce my food budget. Instead of eating out or buying pre-made foods I went all staple crops and freshly made meals. I save over $100 a month, and as a side benefit, have lost over 10 lbs.