Normally when you have such a clause in a contract, it's interpreted by a court as being a surrogate for the actual damages the court would normally allow to be paid if you were to go to court. It's normally viewed as an agreement to the party of the amount that will become payable if there's a breach. It's a contractual agreement. You don't go to court. You have an amount that's specified in a contract, and that's the amount that's payable, regardless of what are the actual damages suffered by the one party.
On February 12th, 2013. See this statement in context.