Being retired, I've volunteered a few times for UPS during the holiday season as a "jumper" I sat in the jumper seat and delivered to one house while the driver delivered to another.
During the holidays the trucks were jam packed as I'd assume much like they are today. Next day air packages usually had their own section in the truck so the driver can streamline those deliveries. However due to the truck being so packed the packages weren't in the section they were supposed to be. I've witnessed on several occasions that the driver spent a good 20 minutes shuffling boxes around only to come up short. Usually results in wasted time because they have a schedule to keep, which means the unethical decision was made to skip that house by reporting that the package wasn't on the truck, or in the case of next day airs, they mark it as attempted delivery and move on.
The way that they use scanners to track and load packages onto the truck, there's no doubt in the drivers mind that the package is somewhere on the truck, but it's not where it should be.
By the end of the day when most of the packages are delivered these packages are found (as you would guess) in the wrong spot on the truck.
I don't have an ounce of doubt in my mind that a variation of this scenario played out in this case. The driver doesn't want to get dinged, and the easy solution is to mark it that way in the system... the question becomes, who's at fault? The driver? because he lied? Or the company for setting such high standards to where they discipline drivers if they miss a delivery time? When corporate sits down to a meeting and sees a chart with missed deliveries, they're going to ask a lot of questions and make the managers to do their job and come up with a solution... in order for management to keep their plate clean, it wouldn't be too far fetched that they encourage such behavior from their drivers.