At one point or another, most people will have to be in some kind of negotiation for a big ticket item. The most notorious of these negotiations is the car. Car salesmen have become famous for their underhanded negotiation tactics. There is an actual name for one strategy that car dealerships (and other unscrupulous types) use. It's called defense in depth.
A surprising amount of negotiations involve simply being willing to outlast one's opponents. This means that one side almost always has the advantage, as being paid to sit in a chair and argue about car prices is a stronger position than giving up weekend after weekend to sit in a chair and argue about car prices.
The most famous car negotiation scene comes in the movie Fargo, where a low-rent car salesman tries to swindle a couple into paying for "Trucoat" rust protection. At one point, the guy goes back to his boss's office, promising to work it out with the boss. He makes small talk about football games with the boss, and comes back with a counter-offer. He also mentions "the factory," and how they impose their own restrictions, implying that they outrank both himself and his boss. Although it's not a straightforward demonstration, it owes something to a famous negotiation technique, called "defense in depth."
What defense in depth requires is time, patience, and a power hierarchy - even if the hierarchy is fictional. Each time negotiations come to a stand still, one side will go to an authority figure. That authority will always approve the current deal, but with one little condition. Maybe a little more money, or a little more time, or a possibility of renegotiation down the line. Then its time to negotiate that one little condition, and come to a new agreement. Because that agreement isn't what the previous authority figure approved, it's necessary to override that figure by going to an even higher figure, who has a condition of his own.
At that point, it's a matter of endurance. Either people aren't willing to sit anymore, or they aren't able to notice how the conditions are stacking up. Eventually, like a boiled frog, they end up with a deal that they (and a host of fictional people in the negotiator's organization) agreed to, but doesn't resemble anything that they agreed to at the beginning of the session.
[Via Bickering In-Depth.]