Anyone in the US can go to a library and borrow a cookbook for free. If you are out of ideas you can do that too.
You realize that there are people who are homeless and who live in areas that don't have any support systems for homelessness (e.g. homeless shelters), right?
You have proposed that a homeless person obtain a phone, find a library that'll mail books, obtain a mailbox, have a book mailed to them, presumably pay for return postage, all so they can obtain recipes to cook on a stove they don't have with utensils they likely lack with ingredients they can't afford.
Homeless people aren't in that situation because they needed someone to write down "how to make rice in a pot", nor are they likely to have discretionary income for your proposals.
And I feel like you do not understand that the average American is not homeless.
If you are homeless you are not going to be a person who is spending >$40/mo for food and needing a cook book to make cheap food interesting to eat. You will just buy cheap food until you bootstrap yourself back to a house and a stable job.
People who spend >$40 per month on food who live 40 miles away from the nearest library.
But of course, there will always be people falling through any cracks. That does not mean that the original piece of advice isn't sound, though.