I think it's a difference in the Short Set, lots of hype for generally good eye appeal coins...vs.... ie early dates and differences in collecting.  San Francisco in Higher Grades, including coins not mushy or soft struck will command big bucks...that said, the 1947 should be reasonable in MS 67. Where those asking prices or confirmed sold? A rather larger number of 1941 Walker Proofs were for sale at several sources...over half I noticed have been sold. Too many reasons to think why some price like they do.  A dealer friend mentioned that he was getting busy and met with 2 new couples in one week, just getting into Silver Bullion, Gold Bullion. Back to your 1939-S...That is a huge difference...