One of the possible replies to the problem of Unix programs exitingnon-zero for clever reasons is that all ofthese special cases and clever reasons are clearly documented in themanpages for the various commands, so all of these problems are not thefault of the authors of the commands.

This view is objectively wrong. The clear, well established truth isthat people do not remember weird little exceptions and funny littlecorner cases in what your program does unless they use your program allof the time (in fact, unless