In part, I think you're overestimating how difficult it would be for you to gain access to customer data covertly, given root access to all the servers at your company.
If I even log on to one of the audit servers without prior approval, it will page the security team. And if they can't validate why I've logged in there, they'll lock out my account.
Plus, breaks are never done through the strongest part of the wall.
Computers can be made totally secure in management minds, and in the minds of the broader public.
We know from stories of break-in after break-in to some of the worlds top companies, that that is a dangerous lie.
Most of these break-ins were done without the conscious cooperation of anyone inside who had admin rights.
Now, just imagine what can be done calculatedly with admin rights.
It comes down to trusting people eventually. It's always about people.
Even though I have server admin rights, I can't touch the network so I can't open an unaudited path to the server.
It's not that the server security will keep me from accessing the data, but it will keep me from accessing it without being discovered.