Even a poor person today has access to potentially far more labor-amplification than anyone in the past.
Things like security, power, status and time(freedom) were always at the core of what it meant to be rich.
But do are new technological societies offer more of those things ? i'm not sure.
No.
http://www.ers.usda.gov/AmberWaves/September08/Findings/Perc...
http://theintrinsicvalue.com/research/food-inflation-how-muc...
You can feed yourself for less than 1 hour of minimum wage a day. At no point in history has food been this cheap.
edit: Just in case this becomes a thift-fight, my $20 is relatively high as I was eating +2500 calories a day (running and bicycling a lot). And most of the time I'd be under $15, but the remainder would be spent on treats.
If you are buying food on a minimal budget, you go calories per dollar (which I'll abbreviate as C/$). If you have money left over, nutrition per dollar.
Set a target - if you want to spend $14 a week, avoid buying foods that do worse than 1000 calories/dollar.
Sugar is 4000 C/$, flour and rice are about the same. Olive oil is 1000 C/$. Ice cream, 700 C/$. Oatmeal, 2000 C/$. Whole milk, 500 C/$. Potatoes (even instant flakes) and peanut butter are also good deals. Eggs and beans are cheap protein.
Vegetables are a bit trickier. Kale for instance is only 140 C/$. An all-kale diet would be $100 per week! Wheat sprouts were the best I could find at 400 C/$ (and that jumps to 700 if you can find a local supplier). Fruit is also tricky. Grow your own if you have space. Raspberries have great yield, require no effort besides picking them and grow almost everywhere. But I'll assume this is not an option.
Meat is stupidly expensive per calorie. Spam is one of the better deals at 400 C/$, but I do have standards.
So anything cheap becomes a staple. Work these into being a large part of every meal. A lot of my breakfasts were "something on oatmeal" and a lot of my dinners were "something on rice". But the more you fill up on the cheap stuff the more money is left over for nice things.
The nice stuff you "ration". For example, I limited myself to at most 8oz kale and three pieces of fruit a day, as well as 8oz of nice steak a week.
Of course, budget a few bucks to flavor - soy sauce has no calories to speak of but it makes rice much more palatable.
Probably the biggest way to save money is to never eat any food you did not make your self. Lots of clever ways to do this. For example, lunch at work: fill a vacuum thermos with rice and boiling water, and it will be done in 90 minutes and keep hot until you eat it.
Can I afford to eat out all the time? Sure. But I like to cook and this is a fun little numbers game.
Our approaches aren't all that different as I cook all my meals at home now, but because I've forced myself to do this, I allow myself to buy whatever I want at the store. This gets especially expensive at the specialty meat store.
Meat's expensive, but that is still a huge sum for just one person. Do you eat a lot of prepared food as well? Snack foods, boxed cereal, frozen prepared meals, etc.?
I spend between $100 and $150 a month feeding my family of four. Very little meat, lots of fruit and vegetables, eggs regularly, beans all over the damn place. The most expensive things in our diet are nuts, and next in line is the eggs/dairy.
And honestly, we only spend this much because we're not very disciplined. We could fairly easily keep our bill under $100 a month with better storage and more reliance on bulk foods.
I have no doubt that I could easily get under $100 a month if I had to, but I love food, love to cook, and have the money, so I see no reason not to spend that money on food.
As for the article, it starts off with good logic but then tends to be oversimplified and ignorant. There are many variables that have to be considered when discussing this type of subject and efficiency is just one of them.