[Puts]

I think the confusing thing is that in a typical unix system we have the same separation for users of processes and users of the physical device. In the physical world, maybe the user-abstraction should be something physical? Maybe the OS should not handle physical users, but instead every physical user brings their own storage area protected by symmetric encryption (either in the form of a USB/memory-stick or a separate partition on a hardrive)? That would be a concept that more would resemble how we think of personal belongings in the real world. Just like I can share an electric tooth brush but I bring my own brush head.