TCC does not bypass Unix file permissions. I don't know where that idea is coming from but it is incorrect.
An admin has always been able to sudo to bypass normal Unix permission checks. That's true on all Unix systems.
An admin has always been able to sudo to bypass normal Unix permission checks. That's true on all Unix systems.
All of this smacks of different parts of the macOS core team not understanding their security model. One half seems to think Full Disk Access just means "has the user's file system permissions instead of sandboxed access" (hence why Finder has it), while the other thinks it means "access the whole disk, regardless of other permissions". Both interpretations are reasonable but become unreasonable when combined into a single system.
Can an app given full-disk permissions not access data in other user folders other than the user who started it?
This is why I'm so confused.