The public perception of computer systems is that they are mindless robots who interpret commands from operators literally and then follow through with them relentlessly, even when the operator realizes he made a mistake. There is actually a lot of truth to that perception.
Reminds me of a rhyme from one of my college computer science professors:
I truly hate this damn machine
I really wish they'd sell it
It never does quite what I want
But only what I tell it.