Organized retail theft rings. Both the stuff you see on the evening news where a group grabs everything off the shelf at an Apple store and one off thefts from places like Best Buy.
The fact that Amazon willingly participated in this scheme is a strong indicator that they were getting a high volume of charge backs and returns that they had to eat because the devices were new in box but couldn't be activated.
Couldn't Apple just enable Activation Lock for the IMEI or serial numbers of the stolen devices? Maybe the retailers are not able to report the serial numbers / IMEIs of stolen devices back to Apple?
The fact that Amazon willingly participated in this scheme is a strong indicator that they were getting a high volume of charge backs and returns that they had to eat because the devices were new in box but couldn't be activated.