The last statistic I heard was that USPS has somewhere around a 70-80% positive scan rate, compared to both UPS & FedEx with positive scan rates at mid-90%. Seems like if USPS is missing 20% of scans, there’s a reasonably good chance that something can get misplaced if a machine jams, a mail bag gets loaded onto the wrong truck, or whatever else you could imagine. The last missing package of mine that USPS found was in a mail bag that didn’t get loaded onto a truck, according to the USPS report. I’ve had a couple other packages that have just stopped getting scan updates and were never delivered/returned. Like I said, it’s possible I just have really bad luck with USPS.Honestly, I can't imagine how it would fail. Tracking shows every step of the journey and would know the postal carrier at the end destination. Prior to that, it's all handled between sorting centers that wouldn't allow individual handling, much less inspection and opening of a package.