Time sharing and systems like Multix existed before Unix, so yes the work has already been done but you persist in an ahistorical understanding.
That bolded words there, I dont want to be rude, but when you can address each of these in reasonable detail, please revisit that point.
Technical inaccuracy followed by nonsequiter of ideology. A base install of Android or iOS these days actually does a very good job of separating permissions of non-interactive accounts vs what is essentially the user account and sandboxing.
