The problem is that unskilled negotiators think that by making a concession the other party will naturally make a concession in return. Because of the highly competitive nature of some negotiations, an unspoken rule may actually prevent such reciprocity. I’ve heard negotiators say, “if they don’t ask, I don’t offer.” Without any explicit obligation of reciprocity, the negotiator has just made a concession, not a tradeoff. 

Furthermore, some companies do not always think in terms of tradeoffs when working with their suppliers. In fact, some professional buyers speak primarily in terms of concessions. From their point of view, there are some good reasons. Enterprise companies do not have the bandwidth to create a fully tailored agreement with every vendor. By the very nature of their size, they need uniformity. Additionally, the people creating these agreements might not be the ultimate decision maker, limiting their ability to make tradeoffs. More importantly, the person you work with might be so far removed from the end goal of how your product or service will be used that the tradeoffs may seem less meaningful to them. 

Excerpt from Jeanette Nyden’s negotiation skills book.