Except those aren't projects proposed or initiated by the artist.
And property and grocery goods aren't even the same category as IP - You can't consume the same cabbage repeatedly.
> That's the contact.
I think you mean contract, but you are ignoring the social contract here. A "worker" isn't going around advocating their own project(s).
A worker's time is worth their wage. If you're paying nothing, nothing is owed. If you pay nothing for a creation, the creator owes you nothing. That's the contact.