The amount of time required to prepare incrementally larger batches increases at a sub-linear rate. The bigger your batch, the more food you get per unit of wall clock time. I try to prepare no less than 3 lbs of dry beans or 2 lbs of beef at a time. Anything less does actually feel like I'm wasting my energy.
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.
Why should this be the case in principle though? Do economies of scale not apply to food preparation?
The homeowner does not charge themselves rent for their own kitchen, nor for their time.
Does it make economic sense? Yes, when you know that there is a frozen potato cartel: https://www.potatopro.com/news/2024/alleged-potato-cartel-ac...