The film-makers only go to the church if they want to make a strong impression (and it's almost always an old-school RC church, with the big fancy altar and tabernacle and whatnot, rather than the more stripped down set-up with a table & some modern art that you see in most real RC churches) of the formality or seriousness of the occasion. When it's about a likeable or "cool" couple, they get married in wierd pointless places like a backyard or beach or something exotic.