To run with your analogy a bit I occassionally see CEO types with "bodyguards". Because the kidnapping attempt is theoretical and not happened for ten years the bodyguard is carrying the luggage or opening the doors or answering the phone.

The analogy is fairly clear - you can spend the money on security in depth. But humans tend to use those in segments for other things eventually. Banks hav been around long enough that all their bodyguards are now bellboys.