@LeviKornelsen I recall being bemused by the trade icons in the Greyhawk boxed set; kind of neat as background color, but little meaningful effect on play; it wasn't like I was going to follow the chain of imports and exports to figure out the flow of pottery across the continent.
Trade notes work as succinct leads directly to scenarios (this barony produces iron, therefore mines to explore) but otherwise only make sense if trade is a supported game activity (ala Traveller).