Don't let that mislead you. Make no mistake about it, this is a highly automated business with a lot of thought, design, analysis, and most likely, very tightly-targeted software.
With all the talk here at hn about cool stuff like algorithms, scaling, UI design, CPM, etc., etc., etc., I still spend over 50% of my time helping customers move shit from Point A to Point B. That's it.
It may sound old school and boring, but it's anything but. When you're doing so much volume, every little thing matters. And lots of those little things can be dramtically affected by good systems. Here's where you have to get good or die trying. When the smallest mistake turns a 50 cent profit into a $100 loss, your systems must be on the razor's edge.
I bet the routing and error detection software in these warehouses is very sophisticated and handles outlying cases most people would never think of. Perhaps some journalist will take us on that trip with the next article :-)