Yeah, it's a tricky thing. I've actually been involved in translation projects for global software, and the closest I can come to an answer is that they don't really think anything at all... there's several different divisions involved, and each one has bits of the picture, and it all just chunks along without anyone thinking it through end-to-end.

Really, a lot of software development, and of organizational activity more generally, is like that.

All of that said... yeah, the "user googles the error message for instructions" use case is not one that gets taken nearly seriously enough. This is also why you get error messages in dialog boxes that don't support copy-and-paste. If it were, every error message would have a unique copy-able ID code .