Re: "You can get 2,000 calories for a couple bucks." Extraordinary claims require extraordinary evidence. Can you please let us know how can you get 2,000 calories for $2?

In addition to what others said, I buy 2 roast chickens a week for $5 each.

Rice is $20/25 lbs, and 1600 calories/lb for 2000 calories/$

They are 6.5lbs after deboning. Cooked chicken skin on is 950 calories per pound. That is 620 calories/$.

Tortillas themselves are 110 cal, and 4.99 for 100ct, or 2200 cal/$

Rice bought in bulk can certainly be had for that price per calorie with some left over for a little protein. I don't recommend anyone follow such a diet though.

I lived off $2/day in food for a few years in the US. Oat flour, protein powder, oil, and a multivitamin.

My approach was a little more engineered than most people's would be, but definitely possible if maybe you expanded it to $3/day or $4/day.

Rice, beans, bananas, potatoes. It'll keep you alive but it won't be pretty.