This seems to be missing the point. Sometimes users see error messages. Sometimes they're good, sometimes they're bad; and yeah, software engineers should endeavor to make sure that error behaviors are graceful, but of all the not-perfect things in this world, error handling is one of the least perfect, so users do encounter unfortunately ungraceful errors.

In that case (and even sometimes in the more "graceful" cases), we don't always expect the user to know what an error message means.