The problem with this article is that a lot of things that are cheap for one serving go stale before you eat the second. For instance, on day one, he adds some mint which cost ~50p to buy, but he calls 1p because he only eats a little. He does not eat the rest of the mint that week, so it cost him ~50p, i.e. half the days budget. I am poor and eat very cheap. I do that using dry bulk foods and frozen veg. This is imp…
So the problem is often not "I have £50 to plan food for the rest of the month" but "I have an unexpected expense and now I have £2 I found behind the sofa and a bare cupboard/fridge to feed myself until I get some more money".
I also found that when I am poor I am much more reluctant to go out and buy in bulk. Even though it would at least give me food enough to last, there's something scary about blowing your entire budget in one go.
If you are poor it is also harder to get to places that sell things cheaply in bulk (because perhaps you don't have a car) and you are more likely to get things from a corner store as needed where there is a higher markup on prices.