The missing piece here: Applications also don't need to be (and third party apps on most single-user systems arguably shouldn't be) in /Applications. Users can

The missing piece here: Applications also don't need to be (and third party apps on most single-user systems arguably shouldn't be) in /Applications. Users can put apps wherever the heck they like (I keep mine in ~/Applications which even gets the same icon automatically if you create it). Apple could really streamline this because all apps that can be drag-drop installed really belong in one's own home directory, where they'll be seamlessly migrated when you move to a new computer, or brought with you if you have a roaming profile. As it is right now, I just keep both Applications folders in my Finder Sidebar and remember that the bottom one is "mine." In an ideal scenario, users could still drag apps to the "one" Applications folder and if they are not an Admin the app itself would actually be stored in a default-invisible ~/Applications. Then when you opened "/Applications" the system would show you the superset of both locations. This is of course nearly exactly how the Windows Start Menu works except that it always had "installers" do the work of putting those program shortcuts in the respective directories, and only well-behaved apps ever asked which place you wanted apps installed.