T-Mobile for example had a major device theft issue with their mailed in device place for the upgrade program they used to run. No surprise, the process was to unlock phone, turn of find my iphone and send in the phone WITHOUT TRACKING to this random low bidder.
This was early in program, you couldn't turn device in at store (I tried). So I filmed myself mailing the device, because without a tracking number on the pre-printed label and an unlocked phone - 100% for sure these were getting jacked along the way.
If you use a brain dead process like this, you have to be bulletproof every step (mail pickup, sort, deliver, warehouse workers handing $1K+ devices etc).
Of course, the phone was reported as never having been received. Tired of the runaround and with the video I had I simply said, fair enough, I will persue this legally and part of that is going to be asking how many complaints you've received like mine (phone reported not turned in). Bamm, 2 days later I had my money.
Thankfully they then let you turn in at a store and I think started sticking at least tracking numbers on things so they'd have SOME sense of what was supposed to be coming in.