The items in your "list" are there either because you "told" apps to add them or because of OS X necessity (e.g. iTunesHelper).
Rita may have simply installed an application whose normal functioning requires that it always be running. In that case, she wouldn't necessarily be aware that the application had added itself to her Login Items. (Though I suspect a "polite" application would notify the user that, once installed, it would launch upon login, I don't think there's any reason it would have to.)
