It seems totally counter-intuitive to me that only one user of a particular computer can determine what system-wide updates have been installed recently; that knowledge should be available to ALL users, Admin or not.
. Different users may have different Apple IDs and App Store accounts. For example, when my grandson is home from college he uses his own account on his father's iMac. Both of them have their own Apple ID and App Store account and both of them install applications, music, etc. Each has their own Photos and Music Libraries, and each has their unique list of App Store purchased applications, but all the apps are installed in /Applications.
On the other hand, on my wife's Mac mini, she has her own Apple ID and App Store account, but I have logged onto her user account and used my App Store account to install apps and her App Store shows apps purchased on both her account and mine. However to update an app showing in App Store, she has to log onto the App Store account where the app was purchased.
BAS (Before App Store) many apps were installed in the user's ~/Applications file, but some years ago Apple deprecated the use of the ~/Applications folder in favor of putting all apps in /Applications. More recent installations no longer include a ~/Applications folder. I hadn't thought of this before you brought it up but it appears the segregation is being handled by the ~/Library/Application Support/App Store/updatejournal.plist. A reasonable work around.
