Premise: Greatest Hits Volume 1 is a greatest hits compilation album by The Beatles which was exclusive to Australia and New Zealand. The album was compiled by EMI Australia to fill in the gap between "Rubber Soul" and "Revolver" (much like "A Collection of Beatles Oldies" would in 1966 in between "Revolver" and "Sgt. Pepper's Lonely Hearts Club Band").
Hypothesis: The Beatles were lazy and didn't want to release a new album with original material.