Because of your choices. They matter. All of them do in some way. You think you've covered all possibilities, but you clearly haven't. I suggest using a guide you can find them online.
you won't drive into another town if you mean that kind of difference in routes or whatever. You have your story and can collect points and I believe I remember you can make some differences.
Anyway not sure if the discussion makes sense unless they revive the game soon.
Okay now I had read your other comment.