The comparison to "free lunch" doesn't really make sense. The phrase "free lunch" has been used for what it transparently means since forever. Nobody used the

The comparison to "free lunch" doesn't really make sense. The phrase "free lunch" has been used for what it transparently means since forever. Nobody used the term "open source" before it was deliberately invented. There was plenty of software in the 80s and 90s that we could retroactively call "open source," but nobody used that phrase at the time. The phrase "open source" was specifically created in 1998 because the term then in common use, "free software," was too generic and people were confused about what it meant. So a new term was created for the express purpose to have a term with no prior meaning so that a specific meaning could be assigned to it. You seem to think that because "open source" is a phrase you see a lot, it's a generic phrase that was always used informally and grew out of natural language. But that's not the case. It's a term of art that was artificially created with a specific meaning.