True there are differences between fiction and non-fiction. But even with non-fiction there has to be a choice of which details to empathize while making a point I'd think. The slant of the article if you will. So the writer will choose points so as to focus the article in the direction they want. If two people are writing articles about Pres. Obama for example and one is positive and the other negative they will focus on different points or present them in different ways to represent their view. The same thing happens if two critics are reviewing a movie. One may like it and point out reasons why it's a good film and the other could hate it and bring up points why they think it's a bad film. I mentioned genre because if the author doesn't have a clear idea what story he/she is trying to tell (if it isn't in focus for them) then they can't be sure that the reader won't be confused as well. So they (the writer) have to have a focus. At least that's how I look at it. Everyone has their own way of viewing things. It would be a very dull world if everyone had the same viewpoint I think.