And if you only eat those; you're looking at getting deficiency diseases real quick. As for animal products, see below.
Of course one should not eat
only those foods. They are staples and they are far cheaper than animal product staples for the most part. That is my point. You still need some fruits and vegetables for your A and C vitamins and such (just like you would on an omnivorous diet).
You may be right about organ meats being very cheap also, that is something I would have to look into. Nonetheless my point remains, which is that a vegan diet in the US can be achieved at a very low cost.
True; but with a meat-based diet, it is not necessary to eat as many of these to gain all essential nutrients. Ounce for ounce, meat is higher in complete, bio-available protein than any vegetable source except soy; and higher in many bioavailable essential nutrients, such as iron.
Ounce for ounce meat generally has a higher concentration of protein, yes, but a gram of protein from beans is still considerably cheaper than a gram of protein from meat. Grains and legumes are also pretty high in iron.
Although many vegetables have these in reasonably high concentrations, their lower bioavailability makes it necessary to eat higher quantities more frequently to obtain sufficient amounts of them.
Honestly I don't know a ton about bioavailability in plants vs meats. I would like to learn more, though. Do you have any specific figures, like for example, iron absorption rate in black beans vs iron absorption rate in lean beef (or any example you like)?
Not true. Meat is remarkably cheap in many parts of the US; especially if you avoid the premium cuts. Organ meats in particular are extremely cheap. I can go to the supermarket and pick up a pound of chicken hearts or beef liver for considerably less than it costs me for a pound of peanut butter.
You may well be right that organ meats are very cheap. Rarely do I hear anything about them being eaten, so I imagine they are cheap due to low demand. To nitpick just a little, we should note that a pound of peanut butter contains considerably more energy (kcals) than a pound of beef or chicken hearts. It has more protein than a pound of chicken hearts, but slightly less protein than a pound of beef hearts.
Dairy products also tend to be very inexpensive; and cheese is an excellent way to supplement a diet poor in certain amino acids and vitamins.
I won't dispute this. I'm not going to claim an omnivorous diet can't be cheap. Still, legumes are cheaper than dairy and you can get all the essential amino acids from them.
It is for the vegan diet I was explicitly referring to. If it's not 100% animal free, then it's not vegan, by definition.
I don't think most vegans claim to be 100% animal product free. The way I understand the term, we avoid animal products to the extent that is reasonable and practically achievable (of course those who consider themselves vegan may disagree on the exact meaning of the term but these are just boring semantic disputes as far as I'm concerned).
If I were to accept the more strict usage of the term and someone were to say to me "I would go vegan, but it's too hard. I can't manage achieving the level of being 100% animal product free" I'd say "Okay, don't go vegan. Just give up all obvious animal products and don't stress the rest." My mindset is that any reduction in animal product consumption is a good thing.
There is a lot more effort that goes into even a vegetarian diet; let alone a vegan one. For starters, balancing amino acids is something that a lot of people simply don't think about; but which has to be done with a vegan diet. How many people know how to do that? No vegetable source has a completely balanced amino acid profile and concentration, except soy, and to a lesser extent, amaranth.
But most plants contain every essential amino acid. I don't know why people make these claim about "balancing amino acids" and "complete proteins" so often, unless there is some bioavailability issue I'm unaware of. Every time I've tracked my amino acid intake I've been fine, except maybe a little low on methionine once in awhile (but not super low). I was raised vegetarian and have survived without putting effort into protein balancing thus far with no major health problems that I'm aware of. I do eat soy once in awhile, but I've never treated it as a staple food.