To prevent abuse where you would sell food to yourself for 1 gold, and then buy food from yourself (from the region warehouse) for 999 gold or such.
Ah, so the gold would've been treated as a negative trade balance, taking out tax gold from the region before it got distributed at the next tax day?
However, I think this is a bit of a relic of the old system, back when wealth was at the realm level. I wouldn't see it as being as much of an issue now.
However, a good solution could be the "donate food" feature I requested a week or two back.
It makes sense to not allow 'selling back' for an automatic trade offer (from Warehouse.php), if that affects trade balance as outlined above. However, for an explicit caravan offer (from CaravanOffers.php), posting a buy order immediately takes gold from the region lord. Thus, selling food back this way would end up with the lord simply getting his own gold back, without affecting region tax/trade balance, no?
I'm guessing the coding is less complicated if both methods are simply disallowed.
