But the average user has no idea whether a system is "using off-site backups with different trust roots not sysadmined by the same sysadmin." And even if it was

But the average user has no idea whether a system is "using off-site backups with different trust roots not sysadmined by the same sysadmin." And even if it was like that at one time, they have no way of continually auditing the system to confirm that, at all times, that process is in place. And they have no idea that two sysadmins aren't in cahoots with each other. That's not a good basis for a robust system.