My brother works in loss prevention for UPS. You would not believe the stories he has when it comes to theft... even by the drivers... and especially of Apple products.
There was even one story of a guy who drove for UPS but also had a business of his own. He delivering in his own area. He would take other packages and shove them in larger packages going to his own business... then tape it shut. Wooosh... gone.

There was this UPS driver that stole an iPad from a doorstep 2 days ago... after Fed Ex had just delivered it. Video included.

At the UPS facility they have to lock up this stuff overnight. They can tell by a glance what the value is by the last digits on the code.