[danpalmer]

> restaurant food is 7 to 20x more expensive than home cooked

I suspect Efficiency is Everything is measuring a very different thing. They seem to focus on calories per dollar, which is not how restaurants or home cooks typically think.

The rule of thumb used in the restaurant industry is 30/30/30/10. 30% for food, labour, rent, and 10% margin. Anecdotally, for dinner I spend about £3 a meal to cook at home, and could probably buy that meal out for £8-12.

As Efficiency is Everything says, you can live on $1.50 a day, but it requires using only a very limited subset of ingredients and allows little room for preference. For some people this makes no difference, for most it's a huge handicap, which is why it's limited to the min-maxing fringes.