I'm going to take the time to validate any kind of split in a logical way, so people can stop claiming that it makes no sense to have a split.
Theft Prevention:
NPCs that you get your trade pack certificate from give the owner a code, this code specifically matchs each trade pack. When you take it to the turn in NPC they expect the code with the tradepack. If you don't have the code they choose to give you whatever split the game is choosing to use and hold the other portion for the player with the code (trade pack owner). This is a realisitic system, and a very good way to stop theft, since robbing physical goods becomes meaningless without knowing the actual code. Also realisitically the goods that were stolen could also be fenced for a fee, since using such a system it should be nearly impossible to trade in goods that don't belong to you. This is also why a split should exist as traders are not given a fundamental way to ensure or protect their goods from theft. If traders were given such a simple verification method then I expect pirating would dwindle into only the most desperate players trying it. The truth is the game caters to pirates right now and any situation where traders were given legitimate tools would result in the extinction of pirates. The split makes perfect sense and actually allows pirates to exist while severely punishing traders. The truth is the game has to, as many of you so eloquently put it, hold pirates hands or "carebear" for pirates. The games lack of trading elements, in a sandbox game none the less, is what allows piracy to exist on a fun level. In any realisitic setting piracy of trade goods would slowly or quickly be almost completely eliminated. Next time you complain about the split consider this and be glad the game holds your hand while you are out pirating.
80/20 seems like it is a good fix to prevent traders from dumping goods early, but that is all it is for, when the real problem is the traders don't need to visit the merchant to collect their part. Of course players would, without a time limit on collection, still dump goods with 60/40 and just go collect later. 80/20 is necessary to help prevent dumping goods becoming more profitable than trying to deliver goods. That is the only reason I agree with it.