I have a question about movie western music. Hymnals in the 19th century had hundreds of hymns in them, but in westerns, any time you're in a hymn-singing venue like a church service or a funeral (or, most memorably, a temperance march) they only know two hymns: "Gather at the River" and "Bringing in the Sheaves"? Likewise, those old player pianos had huge rolls and each piano came with dozens of rolls. They could go on for days without repeating a tune. Yet in movies, any time someone walks into a saloon, it's always playing either "Oh, Suzannah" or "Buffalo Gals." Of course, this goes for other eras. In any movie about the WWII era the background music is always either Glenn Miller or the Andrews Sisters. If it's about Vietnam the music is always the Doors or the Rolling Stones, and only two or three songs by them. Is this just lack of imagination or is it a shorthand way of establishing the era?