Many investment houses tape (by law, house policy, or both) all telephone conversations on their dealing desks. Every employee who picks up those phones (or interphones) knows every word is taped and subject to review.
Observations:
1) This didn't save certain dealing houses from making bad trades which resulted in economic calamity (finance equivalent of crew-induced air crashes).
2) The taped employees know there are far too many hours of tapes for management to possibly review every hour and word. Thus, the odds of any personal conversations being exploited against the participants for non-safety-related reasons = low/approaching zero.
3) No labour law or union contract forbids this practise, based on disclosure and consent.
Yet there are benefits:
It deters certain behaviours and statements from being made during business hours, on company time. And ensures a record is available in the event of any "incident."
There's no inherent reason CVR taping and review should impair flight safety - on the contrary, it might deter off-topic behaviours and help with early detection of problematic tendencies. Panacea? No. Public interest in detecting violative/dangerous tendencies? Clearly. Cultural resistance to such practise? Understandable.