Why Stormtroopers fall into a classic process mistake

I watched Star Wars with my daughters at the weekend for their first time.  I first saw it when I was seven, and can still remember the excitement of seeing it with my uncle, cousins and older brothers.  34 years later, it is still a great film, even though the Imperial Forces were heavily armed all the way around the Death Star but never managed to get a shot onto any of the heroes/heroine.

All very interesting, but in terms of Process, so what? 

There was one scene that really stuck with me on this viewing.  Princess Leia is rescued from her cell on the Death Star, but then she, along with Luke, Han Solo and Chewbacca are stuck with no way out other than through where the Stormtroopers are firing at them from.  So they shoot their way into the garbage disposal system.  [Note, this is a utility system].  Now the stormtroopers don't bother going to investigate even though the shooting has stopped and the only place the escapees could go is into a closed system.  Instead, they reckon that they are now in a system they understand, and just initiate the compact intruders operation in the garbage chute, and assume that the problem has gone away. 

So the lesson as far as I am concerned is not just the obvious - if you are designing a foolproof process, don't forget all the potential hazards.  No point in having a system that can destroy entire planets if it can't handle small fighters, especially as based on the first film, there was no evidence of the rebellion having many big fighters, at least not at their rebel base.  And it would be good to train your staff to deal with the hazards, and not let 5 intruders wreak havoc in your system.

But also, don't forget the utilities systems, even the drains.  And don't assume that they just work, because for all their lack of glamour, it is generally regarded as bad if you can't keep production going because you have a blocked drain. Or that the pump system emptying the drain has failed and you didn't notice.