Lets say you run a taxi service. You pick up passengers to take them to a concert and the taxi breaks down, and instead of the concert, you say that you can limp to the dive bar down the street instead, and the have a band that only has a 30 min set left. Should the passengers then have to pay the full fair? Cause I would expect that they would be paying nothing with an extreme apology. That is what you do when you run a business.