True, and I dislike going to dealer's as well and being charged too much, but I have a few mates who are mechanics at dealers and they tell me that quite often the manufacturer will inform the mechanics of certain minor faults/issues with vehicles that private mechanics don't know about, and often they will fix/upgrade minor parts to save face of a major warranty visit later down the track.
And I guess it stands to reason that because they see so many of the same vehicles come through, that in theory they should be able to perform a more efficient service. (In theory).