> All of the examples are apps where the main use is manipulating files on the system.

So do users, still can't overwrite system wide settings without first getting root. Decent sand boxing has to be granular enough to cover partial access. Of course the hard part on Linux would be locking access to files like ~/.bashrc without completely blocking access to the home directory, that probably would require an exhaustive list of all config files that are directly stored in home instead of a specialized sub folder.