They say that it doesn't matter what you say, it's how you say it, still it seems that authors manage to make it so that it doesn't matter how they say it, but it matters what they say. All the characters gain so different personalities not from how they converse, but from their views and opinions. Everything that is said is said through the author, and therefore it must be hard to maintain any personality within the dialog if not through what is being said.
Sure, some characters can use specific words more often than others, they become a signum for these specific characters, but their personalities through speech don't go further than that as long as only one author is involved. Maybe books with conversations should be written by multiple authors, so the things that are said are done so differently for the different characters,but with such differences, would the writing still hold the same consistency? It baffles me, and provokes me to think more.