We used to send loads of stuff out by carrier, ebay sales mostly, and used various carriers. As you would expect with today's standards quite a bit went missing and the stock reply from all the carriers was "it's been sent signed for and we have a signature". In other words, the postie or delivery driver can chuck it over a wall, open it and steal it, sell it on as a lucky dip or whatever and just sign the ticket. That's the carrier in the clear
Also, many, many years ago, when I worked on the trucks, I used to work for a carrier. The truck workshops (where I worked) were in one end of the warehouse, every day a certain bunch of drivers would offer stuff for sale

They knew exactly what was in the parcels (mostly electrical goods, watches etc) and this was carried on quite openly. Management didn't bother them at all, they would walk past directors / owners with the goods in their hands.
I didn't stay there long, it wasn't really my cup of tea, I left and went working at a truck main dealers. Talk about chalk and cheese, the whole atmosphere was better, it was straight and genuine.