It's interesting; the behaviour you *want* is one that is traditionally available in Windows and is hated by all right-thinking (i.e. unix) people everywhere, since it allows the normal user easy access to destroy the OS.

traditional unix systems clearly differentiate between one or more "users" and the special user "root", which is all-powerful. This helps, in that you have to take positive action before you are able to damage things, so reduces the chance of accidents.

more modern facilities like sudo, available on the tablet, and roles & privileges, tend to blur the line somewhat.

and, of course, a dedicated single-user tablet, where Nokia have gone out of their way to *hide* the fact that it runs Linux, makes things very blurry indeed.