[thegrif]

I have a bit of inside knowledge of the subject having worked for UPS and been out during Christmas time delivering packages. Here is what happens:

Drivers get in trouble if they miss a commit time. To avoid getting in trouble, they will scan the package and mark it as delivered - which results in the delivery status being updated. When they make the actual delivery, they will not scan the package (because it's already left the driver's possession according to the earlier scan).

All package tracking is done based on scans/events. Some of those scans are of the actual package (like above), others are based on inheritance (a trailer containing 500 packages leaving San Francisco will show that data replicated down to each of the packages). UPS only publicizes a portion of the tracking data to its customers - there are events captured at a much more granular level of detail that you can usually get out of CSRs if you call and inquire.

:-)