I think this is what it’s meant to be about. “How do I afford a good amount of protein with not much money?”, is the question it’s answering.
It reminds me of a Reddit post I read several years ago where someone shared their advice on how they managed to live under extreme poverty. They spent a good amount of time talking about what foods are the most cost effective to buy and this chart lines up with what they have been saying pretty well.
They did not say that though? You want politicians that are both good at doing politics as well as be able to properly represent the people they govern.