- Protection against insider threat.
- Protection against leaked credentials.
- Protection against knowledge gaps.
- The psycology of giving a reasonble account of yourself when being judged.
- Assurances that standards are being followed.
Trust is all fine and well, but what happens when one of you're colleagues is having a bad time at home? What happens when their wife is held hostage until they insert some code? What happens when a laptop is hacked?
A cursory glance might just be enough, but you also might want to internalise just why we do these things. Often people won't mind if you set expectations and write the reasons for doing things down.
Also keep in mind all the big breaches that have happened lately. I wouldn't be suprised if they were high trust environments, still got hacked though.