What you mean is life writes the most implausible stories.

As for the story in THE GHOST WRITER, I don't think it's meant to be taken as literally true or possible but a kind of satirical commentary on recent events, making use of devices from movies,with clever updates, like the sinister chase or pursuit that is guided by a GPS system. There's irony even in the setting, which can't be literally where it is but is Germany standing in for New England. I take it we know that and are expected to know that. As when Cary Grant or James Steward played lead roles in Hitchcock films, were' expected to know that Ewan McGregor is a super famous movie actor (from STAR WARS) playing a writer. IT doesn't matter, because the man he has to deal with is a fraudulent British leader, and Pierce Brosnan (very good) is not a real leader, but an actor, which is okay, because the leader he is playing is a fraud.

I always say it's risky to say a story isn't believable or "couldn't have happened," when, as you show in your example real events are just as implausible if not more so. THE GHOST WRITER is for a general audience but a sophisticated one and that kind of audience knows stories or movies aren't copies of literal events but commentaries on them.