Compromise Rambling

In American Heritage, I had to study up on the Constitutional Convention of 1787 and understand all of the points of view, the issues, and the hardships that go into making a government.  Points such as "who has the power, and how much should they have?" were asked time and time again.  How was the legislature to be elected?  Representational votes?  Popular vote?

Well, in the end, we all ended up with a government based on a compromise.  And this led me to think: a lot of things are formed based on compromises- nearly every law in the United States has compromise, everyday business deals made are compromises, legal issues, and even talking to your teacher about your not so good grade can end up in a compromise.

Most nations have a history of compromises, especially the United States.  When the constitution was first being formed, no one knew how to deal with slavery, and whether slaves get to represent the state they live in, and so the Three Fifths Compromise was formed. Again, on the issue of slavery, there was the Missouri Compromise in 1820, in which states below the 36 30 boundary were to be slave states, and future states formed above this line were to be free states.  These two compromises on slavery were made to appease both sides of the argument on slavery, yet the South still became angry with the North about their lack of support for slave states, and proceeded to secede when Lincoln became president.

So, not all compromises can end with a peaceful resolution, like the Great Compromise which formed our government as it is today.

But why do compromises happen?  Is there not a straightforward right and wrong path in every decision we make, business or ethic?

Let's take this example:
A guy lets his friend borrow a car to her hometown(let's say...6-7 hours away) for the weekend because the car owner was not going to use it.
So the friend drives the car down to the hometown, spends the weekend with her family, and then begins driving back.  However, the car begins to break down, and the friend of the guy freaks out.
The engine is fried, meaning there will be a large cost for repairs.
So who pays for the car's repairs?
On one side, the person who lent the car is the owner of the car, yes, but the friend of the owner was driving it, and had already driven about 7 hours down to her hometown.
Perhaps the stress of the car for driving too much had ruined it, or perhaps the car was not in good condition in the first place.
The worst part of a situation like this is that there is no definite wrong or right answer to this kind of question.  Or is there?