It is only a good audit trail if the audit log can be trusted, though. Given how "secure" things like faxes are, well, that's a thing for another day, I suppose.
Very few things out there in today's interconnected world really provide "hard" security, instead of security theatre/CYA/minor deterrants/"keeping honest people honest".
That is not to say that these things have zero inherent value, at least in my mind, but they are not IMO to be confused with high security (as in military grade versus making a few clever [socially engineered] phone calls).
Even so, much of the modern day business world relies on these things to some degree or another.