Comment 28 for bug 861171

why can't the greeter just say, "X user(s) is/are still logged in. Please log out of all accounts before attempting to shut down or reboot." and ignore all the nastly permissions stuff??

If an admin really needs to shut down, it's easy enough to do via terminal or tty. are there really daily use cases where a standard user needs permission to shut down if other accounts are still logged in?

i think we should also consider whether those "other accounts" are most likely to be guest sessions, anyways...