Who thinks that except maybe some very small, very ignorant and insignificant minority of people? I don't understand why people feel the need to point this out - everyone already knows this.
It is not that "people know that money does not come from cornucopiae": it is more that they are supposed not to hold the idea. Or: it should be implicit knowledge, not explicit. Or: you do not need to think about it to avoid dreaming that "streets are maintained by volunteers" (for lack of more absurd insanities at hand). Or: it's mental hygiene not to be delirious and work through a "yes/no" system - you are supposed to have plentiful buffers that avoid you holding weak ideas...
Edit: or, if really that is something you find in society, you have a big elephant in the room (education) with priority over trains and everything.
You know that (the software application) Audacity is free (in some sense of "free"), because in your exploration you found the notion.
You do not need to know explicitly that Audacity was produced our of an effort that cost resources to the developers and other facilitators, because the proper mental process involves much more that you do not develop the opposite idea.
There may be again a link with the words of the late Prof. Patrick Winston: "Intelligence is that you do not need to run around holding a bucket full of gravel to reliably imagine what would happen" (not literal quote).
The same could apply to what you just said. If everyone knows it, presumably everyone knows what you said, as well.
Tl;dr: this is a silly line of reasoning.