Only if you wish to cause a scene for no reason. Human history is full of war, but the average human would prefer to trade for clothing than fight for it. Here, I found that they do not barter directly, but measure the worth of goods in numbered papers. Only at a 'pawn shop' can a customer barter goods themselves, and they receive this paper currency in return. I think this is why the Arcana supplied us with some, as it is the only thing that will buy us food.