Believe me, I know whereof I speak in this case. Booksellers don't own the inventory (that's basically true of every retailer...) but they do want the sales. Since books are both bulky and perishable, a huge amount of attention is placed upon just what gets ordered, just where it should be placed in the store, and just how long it should be allowed to remain there. In quite a few stores these days, the computer-books section is down to just one or two rows... computer-books simply don't pay.
Let's face it, Sweet Savage I-Want-Your-Body Hunk, or anything by John Grisham, is going to out-sell anything at all about Ruby... and continue doing so for a very long time.