Like you, I strongly reject the idea that literature means anything and everything the reader wants it to. Nobody really believes that, even if they say they do. Just try interpreting the English professor's exam directions however you like and see what happens.
However, you must admit that there is some subjectivity involved in literature. Maybe no more than in programmers.stackexchange. But that has the benefit of spillover from StackOverflow, where the right answer proves itself by executing correctly.
That's an interesting point and I agree with what you say for a simple question and answer. But there may be just as much subjectivity in the "right" answer for a complicated problem.
What if it compiles but gives erroneous results? What if it compiles and gives correct results, except for a certain day of the year? (see http://news.ycombinator.com/item?id=4128208). What if it compiles and runs and always gives the correct results no matter what, but isn't as efficiently written as it could be?
However, you must admit that there is some subjectivity involved in literature. Maybe no more than in programmers.stackexchange. But that has the benefit of spillover from StackOverflow, where the right answer proves itself by executing correctly.