Android, iOS, and Chrome OS all have security models that are fundamentally superior to what you get on a base *nix system: Fine-grained, application-level permissions which the user can grant or deny on a case-by-case basis.

And before you say that all those operating systems are based on Unix; that's true but it's mostly just an implementation detail. There's no reason, for example, that Chrome OS couldn't be based on an entirely different kernel and still have the same permissions model, and most Unix-like systems don't have fine grained permissions like this out-of-the-box.