The problem with software is that, for almost all software, the only specification for what it is supposed to do is discovered as the software is written. Nobod

The problem with software is that, for almost all software, the only specification for what it is supposed to do is discovered as the software is written. Nobody knows all the data, the data semantics, its dependencies, what output is really required and how that it to be computed from that data. Virtually all cases, and certainly all software I've ever been involved with, all this is discovered on the fly during the development effort. We even encode this into our processes, after all one of the main reason agile and similar processes exist is the understanding that we need to iterate to discover what the spec should be. If a full specification is truly known up front and validated, then building software that works correctly to that specification is a well understood problem with well understood processes (sure, much more time consuming and expensive than regular software engineering, but that is a different category of issue) But look at the Boeing 737-Max8 problem: the issue doesn't appear to have been the implementation of the software, the problem seems to have been that the specification itself was poorly constructed for business reasons. And now software gets the blame? Sigh.