I'm not an econ person, so this is a super naive question, but here goes: why, given the comparative advantage that specialization produces, does anyone prepare their own food rather than buying from restaurants all the time? It seems like there should be economies of scale with respect to food production (restaurants prepare food far more efficiently than I can do at home). Where I live, it's often cheaper to prepare your own food than ordering take out, but I can't understand why.
The weights used in the U.S. CPI (from 2016) are available here: link to BLS weights. Note that these weights are based on consumption data, so that they are meant to align with actual spending patterns.
If you look at them, you will see that the majority of the weight is either processed food or food away from home. Note that some categories explicitly state “processed,” but even things like salad dressing are put together in a factory.
Factories have a comparative advantage for processing food, but not for delivering hot food. Meanwhile, food is normally shipped in a form that can be stored. A box of pasta can be held in a store a lot longer than pasta that has been boiled and put into a container. Households do the final heating steps. As such, the premise of the question is somewhat flawed - processing is being done largely in an “efficient” fashion (although there are debates about food quality).
Restaurants are required to pay workers and rent and expect to make a profit, whereas food prepared (or just heated up) requires no payment. Cooking is labour intensive, and so it is hard to compete against \$0/hour if we look at the cost of the meal. Individuals might value their time at more than \$0/hour, but how they value their time does not matter if they cannot get more paid work and face a strict monetary budget constraint. Meanwhile, travelling to get a meal takes time. Finally, being reliant on food away from home poses risks, as seen in the pandemic.
It depends on two things:
- Do you make a certain amount such that if bought food rather than spend the time cooking and cleaning afterward, you would have saved money? In other words, if you make \$50 an hour, and your meal costs \$20, it makes sense to buy the food rather than spend an hour picking out the ingredients from the grocery store, prepping it, and then cleaning up afterward.
- More importantly, however, can you GET that hour, if you hadn't spent it on prepping the food? In other words, if you're a freelancer, and you know if you spent the hour looking for a job, getting the job, and doing the job, it makes sense. But if you're salaried worker, just because you spent the hour working instead of cooking doesn't mean you're going to get 1 more hour's worth of money.
Also, some people just like cooking their own food, and food you buy outside tend to be high in sodium and fat.
Lets look at the cost of a simple Hamburger.
If I order it at my local pub: The food cost will run about 33 +/-3% of the menu price. Labor is a close second 32 +/-4% For every employee you see there is another in the back of the house. Overhead Rent, utilities build out. 30 +/-4% and finally profit 5-10%
If you cook at home your cost of food is really going to cost you similar to what you could buy at the store. The main difference is the quality of what high end steak houses are buying vs what you can buy at a local grocery store. At home you don't really have a labor cost unless you are reducing your income potential by cooking. Overhead is a sunk cost you are have to pay for
There's little evidence that ordinary eat-in restaurants are more efficient at preparing and serving food than home-cooks.
It is more credible to think that factories are more efficient at processing food than home-cooks, which is why there is nowadays actually an abundance of food in frozen or otherwise prepared forms (including that which is supplied to restaurants).
In terms of hot food, the main inefficiency of doing this centrally would be the travel time (and travel cost) incurred at every meal, and the need for physical infrastructure that is capable of rapid distribution of hot food to a large and hungry multitude. Cooked food usually starts to deteriorate in perceived quality within minutes of cooking being concluded.
Meanwhile, once the preparation of food is done, there is very little to be gained in terms of efficiency whether it is cooked centrally or cooked at home. So in general, the distribution of uncooked food is far more efficient, since it reduces the urgency of distribution (with large spikes in demand at conventional mealtimes), and usually a number of uncooked meals can be retrieved in one transaction with the distributor, and then cooked at leisure.
Generally speaking, the amount of labour required for home cooking can already be reduced to a matter of minutes of active labour, and a few tens of minutes of passive waiting, and it's very difficult to make further economies on this stage of the process.