Firstly, there is no such thing as objective reality for humans
What? This is just silly. You don't know the difference between hypothetical fantasy and real life, or are you just being hyperbolic?
Secondly, the principles that underpin this scenario are highly active in the world today
Still, it is irrelevant since I asked for a real world example.
Not too long ago my neighbor cleaned the carburetor on my lawn mower, and I fixed his router config in exchange
Another contrived example which excludes the entire world. Who made the lawn mower? Who made the router? Literal slaves in a third world country. Surely you are not so ignorant you know this?
whether Person B can get enough protein from coconuts is entirely irrelevant
It is not irrelevant; it is hilarious you don't know this simple nutritional fact.