Bosses are so busy delegating jobs, they have no time to do any work. When someone blows your horn, it sounds like a Cadillc. When you toot, it sounds like a Volkswagen. You can tell some people aren't afraid of work by the way they fight it. People who mind their own business succeed because they have so little competition.
Computers are unreliable, but humans are even more unreliable.
Any system which depends on human reliability is an unreliable system. The only different between the fool and the criminal who attack a system is that the fool attacks unpredictably and on a broader front. Self-checking system tend to have the inherent lacks of reliability of the system in which they are used. The error-detection and correction capabilities of any system will serve the key to understand the type of error which they can not handle. Undetectable errors are infinite in variety, in contrast to detectable errors, which by definition are limited.