I don't see this at all. Staple foods are cheap and abundant. Fruits and vegetables don't cost much at all. Some animal proteins can get a bit pricy (beef mostly) but chicken and pork aren't that expensive. Eggs are like $2 a dozen.
I love my meat but if I switched to a vegetarian diet it would be trivial to make varied, delicious meals at $1.50-$2 a portion.
Where? It's $4 for a dozen eggs where I am and I think that's pretty cheap. It's $5 for a bag of shitty apples. And then another $5 for a bag of oranges, so my kid can have fruit for the week. I cook from nothing but fresh and my kid gets one bag of chips or cookies a week. I buy 2lbs of meat for us both. I still spend over 100 dollars.
I guess we could have beans and rice every day, but I don't think it's a lot to give my kid a varied diet based on what's in season. Out of season is awful and that's how I ended up spending $15 on berries my kid wanted.
When people talk about these cheap meals, I wonder if they just expect everyone to eat the same thing every day at the lowest quality. I can go to a budget grocery store and get $3 eggs. That's true, but I feel like the local national chain should ve a good enough yard stick.