How is that possible? Is anyone here close to spending $21/week for all the food they eat (ignoring luxury items, etc)?
That hasn't been possible for me for at least 20 years, and when travelling to cheaper places (pre covid), it doesn't seem possible there either.
Where are these average food prices?
To put it another way, I am perplexed by the idea that it needs to cost much more than $3/day to feed yourself healthy food in the US, whether or not you have that as your budget. I'm not sure how it wouldn't be obvious that this is eminently achievable without sacrificing a good eating experience. A bit less meat, a little more legumes, and you're done.
I'm guessing 1.5kg of dry white rice can be found for around $1, and that covers the "calorie" needs. The rest of the budget can be spent on vegetables, nuts, beans, lentils, etc. to cover the "nutrients". It would be a pretty sad diet, but I think you could hit the numbers they're looking for.
In that case, I'm having difficulty getting worked up over rice and beans (a tiny percentage of my grocery bill) having a small markup on average in the US.