It was once a common practice of saloons in America to provide a “free lunch” to patrons who had purchased at least one drink. Many foods on offer were high in salt (ham, cheese, salted crackers, etc.), so those who ate them naturally ended up buying a lot of beer.
In his 1966 sci-fi novel, The Moon Is a Harsh Mistress, Robert Heinlein used this practice in a saloon on the moon to highlight an economic principle:
“It was when you insisted that the, uh, young lady, Tish—that Tish must pay, too. ‘Tone-stopple,’ or something like it.”
“Oh, ‘tanstaaﬂ.’ Means ‘There ain’t no such thing as a free lunch.’ And isn’t,” I added, pointing to a FREE LUNCH sign across room, “or these drinks would cost half as much. Was reminding her that anything free costs twice as much in long run or turns out worthless.”
“An interesting philosophy.”
“Not philosophy, fact. One way or other, what you get, you pay for.”
While the phrase “there ain’t no such thing as a free lunch” didn’t originate with Heinlein, he did help to popularize the concept. Nobel-winning economist Milton Friedman even used a variation for his 1975 book, There’s No Such Thing as a Free Lunch. Economist Campbell R. McConnel claims the phrase is the “core of economics“: