djhworld is talking about a scenario where someone at a company knows a certain high-price shipment is coming in. He could talk to accomplices and direct them to the exact truck and intercept/steal the item before it's delivered. Who would know there was a connection between the theives and the insiders?

On a more practical note, I can understand why UPS/FedEx wouldn't want consumers to see this. They would be bugging the hell out of the customer support reps asking why their truck wasn't stopping at their place first, etc. Sure, if the driver is lost, that's another story, but I think the larger companies already track their equipment in realtime. The signature pads are always live now.