[fjtorres]

Amazon retail operates on single-digit margins so the bottom line impact of each error is magnified. Plus it annoys customers and Amazon prefers to please customers over suppliers or warehouse employees.
(Which is why they prefer digital sales whenever possible. And why they automate as much as possible. Well built robots don't whine. I've done *remedial* warehouse work myself. Not much fun. But that's why its called work and not entertainment.)

The reason Amazon makes money off retail is that they minimize the opportunities for error. The more errors they squeeze out of the system the better for them and their customers.