Don’t read the comments, I tell myself, and yet, because I am terrible at following my own wise advice, I read the comments. The article will be about a government project, or a politician’s promise that a benefit is coming for many, or the disadvantaged. Being generally on the political left, I think this is a good thing. The comment will claim this is a bad thing, sagely stating the proverb “there is no such thing as a free lunch.”
In the late 1980s I purchased a copy of The Concise Oxford Dictionary of Proverbs. It’s one of my most-used literary reference books, and while most of the information can now be found online, the book remains easy to use, ad-free, and authoritative, which is more than can be said for many online sources.

The Introduction explains that proverbs once carried much weight, and that “as late as the seventeenth century, proverbs often had the status of universal truths.” After that, proverbs dropped in status, sometimes being ridiculed, and while they are still popular (and still being created), they serve largely “to provide the sauce to relish the meat of ordinary conversation.”
In other words, announcing there is no such thing as a free lunch is not the mic drop moment its users seem to think it is. (By the way, speaking as a former semi-pro audio technician, please do not drop, hit, or tap microphones. “A comedian might think it’s cool to drop the mic after a successful set, but in reality it is damaging a wireless Shure Vox mic that costs a few hundred bucks. And that makes you a douche.”)
“There is no such thing as a free lunch” is noted in the Introduction as an example of a new proverb. It comes from the field of economics, a good reason to be suspicious of its significance, with first recorded usages in the 1930s and 1940s. The proverb was popularized by use and discussion in Robert Heinlein’s novel The Moon Is a Harsh Mistress. Given Heinlein’s politically right perspective, that’s another reason to be suspicious of the proverb. (In my long ago Science Fiction reading days, I recall Have Space Suit, Will Travel as being not particularly good, and while I enjoyed The Door into Summer as a teen, when I read it a few years later I was repulsed by the use of time travel to legitimize an adult-child relationship, and noted the pervasive sexism and the attack on planned economies.)
Proverbs don’t carry much weight, this one is less than a hundred years old, so hardly the wisdom of the ages, and comes out of economics and the political right. Grounds to ignore it completely — but wait, there’s more!
Free lunches were a product of the industrial era. Numerous sources note the tradition grew out of American saloons offering a “free lunch” with beverage purchase, as an advertising gimmick or to skirt alcohol serving laws. It was no secret that the cost of the often cheap and salty lunch was built into the cost of the drink (or drinks) the patrons would purchase. Thus it is patronizing for economists (and online commenters) to make the obvious statement that nothing is free. We know. (Just as we know that free delivery is not actually free, as we add a $15 item to the cart in order to get “free delivery”).
Many proverbs do state the obvious, but manage to be less patronizing. For example, a favourite of mine manages to be both obvious and witty: “Love and a cough cannot be hid.” (Originally Latin, amor tussisque non celantur, first recorded in English in 1325. How did we lose the lovely onomatopoeia of tussisque?)
Though free lunches were not free, they did have a social benefit: “A free lunch-counter is a great leveler of classes.” Next time you hear a social program put down by a comment like “sounds good, but’s there no such thing as a free lunch,” remind yourself it’s a weak and biased argument that states the obvious, “free lunches” existed, and they were a good thing.