It's interesting that overall spending doesn't decrease that much in the end, although shifting from snacks to fruit is the kind of change health advocates have always wanted?
GLP-1 helped me kick my cravings for junk food, but that just meant I was eating more of the "expensive" stuff. Instead of $0.50 worth of Doritos as a snack, I'm eating $1.50 worth of Greek yogurt and $1.50 worth of fruit.
More than a billion asians eat nutritious, cheap and calorie-balanced meals every day, unprocessed.
Staples like legumes and rice don't cost much and are very nutritious. And supplementing with moderate amounts of seasonal fruits and vegetables and moderate animal protein is still very affordable and healthy.
A kilo of (dry) legumes is about $3.50, about 3500 calories (50% more than an average human needs per day), delivers >200 grams of protein, > 100 grams of fiber, some healthy fats and enough carbs to power you and a good set of vitamins.
Hell if you get down to it, vitamin pills to supplement any deficiencies is a budgetary rounding error.
Compare that to either Doritos and you don't get anywhere close. Doritos cost >$10 per kilo, and cost >$100 per kilo of protein, has low fiber, high fat, high salt. It's not nutritious, actively harmful and actually extremely expensive to fuel the body this way.
And it makes sense: processing ingredients leads to a more expensive product than the base ingredients. This is true in every economic sector. Only uniquely, in the food sector ultra-processing doesn't only lead to higher prices for the customer (the reason companies do it in the first place) but also less healthy outcomes.
Doritos are made of corn and vegetable oil. The prices of these ingredients are orders of magnitude lower than the end-product. Corn is like 30 cents per kilo, oil about $1.50. If you want the same nutrients without processing like frying etc, you can eat literal orders of magnitude cheaper.
This is one of those reasons that the term 'processed' food is stupid. White rice is a very processed food - what is the removal of the bran and germ but processing? And many other 'processed' foods undergo processing with the same sort of ramifications for health.
Legumes are also not complete proteins in the majority of cases - soy is a significant exception here. Soy has a PDCAAS of 1, the same as whey, but lentils range from .5 to .7, many beans are around .6, etc., and this can end up meaning your 200g of protein ends up being quite different in impact to many of your body's uses for protein than someone else's 200g of protein.
So a chunk of your protein intake would still be incomplete. It's not like the ratios are perfect so that a cup of each gets you 20g of PDCAAS 1.0 protein. Doing some quick napkin math looking at the AA makeup and protein digestibility of the two, it's like 14g equivalent of PDCAAS 1.0 protein.
~25% is a pretty significant gap if you're trying to hit optimal levels for things like muscle growth, etc.
Red kidney beans (50g): PDCAAS = 0.88, Protein = 11.25g Basmati rice (50g): PDCAAS = 0.7, Protein = 4.5g
Red beans + rice (50g, 50g): PDCAAS = 1.0, Protein = 15.75g
Milk (500g..): PDCAAS = 1.0, Protein = 15.5g
So, from a protein perspective (according to PDCAAS), 500g of milk will give you the same amount of usable protein as the 100g rice and beans meal. There is nothing left on the table.
So, just eating kidney beans, PDCAAS would say that you aren't really getting the full benefit of the "protein on the label". But once you combine it with rice, you are getting the full benefit (according to PDCAAS).
You can't look at the digestibility of the two foods in isolation to make the calculations.
As long as you are eating a varied diet, PDCAAS is pretty pointless. If you have an eating disorder, or food scarcity issues, then it might become important.