I know that many companies suffer from unfair business partners around the world. But they have all the needed document to go to the court and sue them. What warantees will you provide them?
Going to court is a negative scenario (meaning the businesses couldn't resolve the issue internally). That is something businesses can always do - but it of course takes time and it is not always economically viable due to legal costs that arise.
We want to lower the risk of this happening with the trust mechanism - trust rank, because no single business will want to receive negative evaluations that will have a negative impact on their existing relationships with other businesses on the Procurean network (the network will trigger an alarm with their existing partners) and also future relationship from potential businesses that will get discouraged by a bad trust ranking.