I can make about 2000 calories for about $2-5 using staples like rice, beans, flour, salt, yeast, pepper, etc... Generally, spices are pretty cheap. Especially if you go to the bulk section instead of buying the little jars.

The thing I see stopping most people in poverty is lack of access to a kitchen. No oven, no stove, no pantry, etc... A hot plate and a microwave if they are lucky. Also the usual health issues that come from deep poverty like executive dysfunction, depression, and other chronic illnesses.