Shipments are lost for two primary reasons:
Cargo theft is an international problem. Billions of dollars of cargo is stolen every year. In the global economy, raw materials are often sourced in one part of the world, products are manufactured in another, while the finished product is warehoused and consumed in yet another location. Shipments can be stolen at any point, compromising product integrity and availability.
How many times have you personally experienced flying to an exciting location and your luggage does not arrive with your flight? No one seems to have a clue where it is. Turns out, this is the exact same phenomena that effects all cargo shipments. There is no malicious intent, the shipment was just misrouted because of machine or human error.