Don't forget that the ex-employee might be gone, but the guy who hired him is probably still there and doesn't really need documentation of how his judgment was

Don't forget that the ex-employee might be gone, but the guy who hired him is probably still there and doesn't really need documentation of how his judgment was screwed up at hiring time. So there is very little motivation to document why someone is being fired unless you can prove in writing the problem began after hiring or couldn't have possibly been detected in the hiring process. The explanation is silly (does any company REALLY care about its employees much less ex-employees?) but the end result is the same, no point in talking about it.