I just finished a DC 12 good negotiation
Really?!? I mean, you and I are on the same page as far as the subject of negotiations being pretty straightforward, but I don't recall ever seeing more than 10 resources (goods, coins, supplies and/or medals) to choose from.
Meanwhile:
I just realized that there is a definite disconnect from reality here. (Not with you, Razor.) All the players who claim that there is an issue with negotiations are really saying that Inno is actively cheating. And going to quite a bit of trouble to do so. Here's what I mean. Negotiations like this game has (not the C-Map ones, obviously) are pretty straightforward. When each player enters a negotiation, the game is coded to select random resources to be required. Between 2 and 10, in my experience. These do not change once selected. After that, the game is undoubtedly coded to simply tell the player whether each resource they choose for a specific spot is (A) Correct, (B) Wrong Person, or (C) Incorrect. The only way there could be any truth to the complaints is if Inno coded the negotiations so that the correct resource for the remaining slots actually changes from one turn to the next based on what resource the player chooses. That's simply nonsense. This isn't even an RNG issue. There are no percentages involved. The resources required are selected at random at the beginning of the negotiation and they don't change until/unless the negotiation is completed, whether successfully or not. It boggles the mind that some people are so upset at allegedly poor luck in choosing that they have to believe that they have somehow been cheated.
So. First of all, track your 50/50 choices. Actually write down each time you're right and each time you're wrong. For months. What you'll probably see is streaks of good luck and streaks of bad luck. And overall you will see that you're not failing 90% of the time like you all think, but more like 40-60% of the time. Some will be slightly higher, some slightly lower. But over months, the odds are that you will be pretty close to breaking even. There will be rare instances of someone having an extended streak of either good or bad luck, but over time it evens out.
Finally, if you do track your results over months and find that your failure rate is extremely high (75-90%), then fine, come back and tell us. But if you think there is something nefarious going on with negotiations, you're just plain wrong. I'm willing to bet that not one in a thousand will have a failure rate that high.