Managing backups has never been my role, so I'm not too familiar with the technicals of how the various 3rd party solutions manage the keys. My question is: Does the database administrator really need to know the password for the backups in order to maintain the day to day backup process?
My thinking is that the passwords could be held by an executive manager. Even on those occasions where a restore from backup is required, the manager could supply the password remotely without revealing it to the database administrator. This may result in a slight delay of recovery time, but if one person holds the backups and another person holds the key, then one of them acting alone could not compromise the data, even if the password remains static over a long period of time.
"The universe is complicated and for the most part beyond your control, but your life is only as complicated as you choose it to be."