Within this context, "root access" is "root" in the sense that it refers to whatever the highest level of privilege is (the root of the trust chain). It's like

Within this context, "root access" is "root" in the sense that it refers to whatever the highest level of privilege is (the root of the trust chain). It's like a tree where each program/agent can spawn subprograms/subagents with privileges that are a subset of its parents. With root access, you have the ultimate ability to decide what runs on the computer. Including programs that do not have root access or programs that prevent other programs from running with root access. If the highest level of privilege is secure boot (the ability to decide what OS runs on the device), then you can run an OS that lets you read everything off the filesystem, sure. But you can also run an OS that doesn't let you read everything off the filesystem. What matters is that if you have root, you (as a person) are at the top of the trust chain. It doesn't matter if the root permissions trickle down to seated users because you can change that if you're at the top.