If you DON'T scan the discs every day, then you need to organize them in some fashion so that they could be picked from the shelves when an order comes in.
If you DO scan them every day, then they can just go on the shelves in random order. The scanner will automatically pick out the discs that it needs to ship that day as they go through.
So, you pay extra for machines and labor to scan every day, but you save on the added cost for sorting equipment, as well as random-accessible storage units and people/equipment to locate and pull random movies from the stacks.
This makes even more sense if, as others have suggested, most of the Netflix inventory is deployed in the field at any one time, and not sitting on the warehouse shelves.
If you DON'T scan the discs every day, then you need to organize them in some fashion so that they could be picked from the shelves when an order comes in.
If you DO scan them every day, then they can just go on the shelves in random order. The scanner will automatically pick out the discs that it needs to ship that day as they go through.
So, you pay extra for machines and labor to scan every day, but you save on the added cost for sorting equipment, as well as random-accessible storage units and people/equipment to locate and pull random movies from the stacks.
This makes even more sense if, as others have suggested, most of the Netflix inventory is deployed in the field at any one time, and not sitting on the warehouse shelves.