I think it's meant to represent international trading like Australia supplying coal to China IRL, it's not a one time purchase like 'here do you wanna buy these spices?' it represents a long term trading relationship and the gold you get is the value on your end, or access to the resource if you bought it.
It's beyond doubt that this is an intended feature of the game, now it may be that in your opinion it makes for a better game if the feature is ignored. I can't see why so you'll have to provide reasons for that.
Calling it cheating is silly, it's obviously an intended and integral part of the game.