Imagine for example, if someone unidentified got off a bus outside some department store, went in, shoplifted and then left. The store, analogously to Sony here, could well send a letter to the bus company complaining about authorising the shoplifting.

Let's work through a few hypothetical "what if" scenarios to illustrate some common engineering themes related to quality control and the inherent stresses between those who build, those who test, and those who sell. Every engineer is deeply familiar with these patterns, but I believe even the general reader will understand the dynamics better by reading these scenarios.