So if the President calls another official over the secure line and tasks them to falsify election results and then prevents the transcript from going into the archive, how do you even get em? Practically speaking. That's the problem, that's how it works -- use the office immunity, plausible deniability and procedure rules to your advantage. Making it so is asking for trouble, just waiting to be abused the hell of.
It's the same things cops do, jeez.