Amazon Inventory Management, $5 Blu-rays, and books?

I had an epiphany a couple of days ago. I describe it herein:
 

 http://www.technologytell.com/ entertainment/60881/5-blu- rays-blame-amazon-overstocks/ http://www.technologytell.com/entertainment/60881/5-blu-rays-blame-amazon-overstocks/

 

 Basically, it seems that Amazon is in the habit of dumping very new Blu-rays (such as Birdman) within months or less of their release. Presumably this is because their inventory management system calculates that they could earn more money by getting rid of some of their no-longer-needed cushion against surprise release-day orders and replacing it with something that will sell sooner. These almost-new Blu-rays (along with some whose cases were damaged in shipping) end up at a surplus liquidator for $5 each. (Including Birdman, released only two months ago.)
 

 Of course, they don't do this with paper books, since they can destroy or return those for a full refund, but the principle should hold even more true there, since they can get all their money back for their returns. Amazon's computers keep them as close to the razor edge of just-in-time ordering as they can get away with. This is why it hurt Hachette so badly when they got in that fight with Amazon and Amazon stopped juggling its inventory for their benefit...and Hachette was unable to ship books that were ordered in a timely manner.
 

 
 Sometimes, it seems like Amazon makes a lot of its money on pennies' worth of margin at a time...but it does it so fast that it makes a profit on volume. Including by doing counterintuitive things like dumping brand new Blu-rays in favor of newer ones that will sell better. No wonder everyone else is having such a hard time either catching up or slowing Amazon down...