That is because it turns out that everyday software often needs such permissions to operate gracefully. What is wanted is some system that allows one to run u

That is because it turns out that everyday software often needs such permissions to operate gracefully. What is wanted is some system that allows one to run untrusted sofware in without fear of it compromising one's system. — the problem is that the set of software that can be so ran is smaller than expected, as most software by design is capable of making changes to one's system, as one typically uses software for such tasks. A text editor that cannot edit every file in one's home directory would be rather useless, but in doing so, it is of course capable of completely destroying one's system as well. The dream of being able to run “entrusted software” is not a very realistic one.