Comment 3 for bug 861171

you do not even have to be logged into multiple user accounts. On my laptop I cant shutdown/restart if I am even logged into 1 account. Bit silly that not even a message pops up to say "cannot shut down because...".
I think this is a serious usability issue. If there were concerns that the dodge behaviour of the launcher was confusing to new users then this behaviour of the unity greeter will cause new users to lose their minds.