So much this.
Just look on threads here at the advice given to people on how to budget
"Buy in bulk": great if you have the means to transport it, somewhere to store it, and a way to cook it
"Go to a budget supermarket": fantastic idea in theory but I know my nearest budget supermarket (an Aldi) is a £6.40 bus ride away plus £3.20 for any children with me and I'd then I'd be limited in what I could buy as I'd have to also carry it and transport it back on the bus
"Shop online so you can stick to a list/budget": also great in theory but most shops have a £40 minimum spend, you also need a debit card
"Make a huge pot of soup/sauce/curry and portion it out over the week": sigh. a, you need a weeks worth of ingredients, see above for this and b, you need fuel to cook it, and c, you need somewhere to store it and d, there is a mental toll to the monotony of eating the same boring, basic, cheap meal over and over all week long
"Use lentils instead of meat": they take a lot of cooking and if you don't like them or the DC don't like them, that's a lot of waste. If you have £1 and it's a choice between a bag of lentils that they might eat and a bag of 24 nuggets that they will definitely eat, which are you going to choose?
There are so many barriers in the way and telling people that they should just cook these amazing 30p a head meals shows a total lack of understanding about what these are.