When my grandmother married in the early twentieth century, her parents gave her a fairly substantial sum "for herself". In those days, it was almost unheard of for middle class married women to earn their own living. The budget was usually tightly controlled by the husband, who would give his wife a weekly allowance to manage the household expenses.
So it was for my grandmother as well. She accounted for every cent she spent in a little notebook, and even though my grandfather earned a decent living, her allowance was often insufficient to cover all the costs. Rather than discussing her problem openly, she dipped into her personal wedding gift instead, with the result that she depleted it over the years.
Most other Depression era housewives didn't have the luxury of a personal cash stash.
Either way, economy in the kitchen was something that housewives have striven for over the years, inventing all sorts of recipe substitutions and modifications to enable them to spend less money without sacrificing flavour. In many cases, the resulting concoctions were delicious, and they have survived the test of time.
I have a theory that many of the recipes we take for granted today evolved over the years with economy in mind. Grains are often used to replace or augment proteins, but other starches like rice, potatoes, and even pulses, can also be used to reduce the cost of a dish. Some examples:
Meatballs and meatloaf: most recipes include breadcrumbs or crushed crackers. In combination with an egg for binding, the result is a lighter, less dense product, but one that uses less meat. For more on the different recipes, there is an excellent discussion in CookSmart.Whereas our hunter-gatherer ancestors would usually have eaten mainly meat that was prepared by carving it off a freshly roasted animal kill, agriculture allowed humans to develop many clever ways of using carbohydrates to replace increasingly scarce, and therefore more expensive, proteins. One-dish meals like pilaus (pilav) or biryani are all related and are commonly eaten from Central Asia to India. The base ingredient is rice, while the flavour is augmented with a combination of vegetables and protein, usually meat. Often, the amount of meat depends on the relative wealth of the family that is eating it.
Custards: Desserts like crème brûlée are made by cooking cream or full fat milk with eggs over a low heat until the proteins coagulate. A more thrifty custard is made with regular milk and bound with custard powder, which is made of flavoured and artificially coloured cornstarch. Alternatively, the pudding can be thickened with flour.
Cake: Vinegar cake (also sometimes known as wacky cake) is made with vinegar and baking soda instead of eggs, and dates back to at least WW1. There are several different theories about the origin of the recipe, and I think I even read somewhere that it originated in the Civil War, but don't quote me on that. Nowadays, this is a popular way to make vegan cakes.
Sauces and soups: Heavy cream can be replaced with a mixture of flour and milk to recreate a similar creamy texture.
In this way, people with less money to spend on food have been able to fill their bellies, though not always with nutritious foods. In Africa, for example, kwashiorkor is a form of protein malnutrition. The name is derived from Ghana's Ga language, and means "the sickness the baby gets when the new baby comes" - in other words, the older baby is weaned onto a starch-based diet that is deficient in the amino acids and proteins found in breast milk.
Today, meat and eggs can be purchased much more cheaply than ever before, but many consumers have never learned to cook the way our grandmothers did. Many of the prepared foods available in grocery stores rely heavily on grains and starches - think of pizza, cakes, pasta dishes, french fries, chips, as well as pasta and potato salads at the deli counter - and provide hefty profits to the corporations that prepare them.
In this way, we are unwittingly perpetuating carbohydrate-based thrift, even though many of us have more disposable income and better access to high quality protein than ever before. The difference is that today, the corporations and the middlemen are the beneficiaries, and we are saddled with obesity, heart disease and the various other diseases of modern civilization that result from a diet that is carbohydrate-rich but nutrient poor.