If my anecdotal experience of Amazon deliveries is anything to go by, the mistakes may well have been made by a computer - on a couple of occasions I've received the wrong item, then gotten in touch with Amazon whose customer service have apologised big time, then sent me another item - only to have another incorrect item arrive a few days later. Another E-mail to Amazon, another apology, another incorrect item in my mailbox a few days later. My guess is the bins containing the items have been labelled incorrectly, thus leading the poor warehouse worker to pick the wrong item time and time again.

Robots will make the same mistake, only faster. :/