What is the need of the Facetime app in the MAS? Looking through the Mac App Store I stumbled across a result that really confused me. There I saw the FaceTime App made by Apple. It costs £0.99, with minimum requirements of OS X 10.6.8.





I was confused because all new Apple Macs above 10.7 already have FaceTime, so why is it available to be BOUGHT?

Also, as I already have the FaceTime app why did the Mac App Store not tick it off and instead show Open? What app will I get if I was to buy what I already have? Is this a listing that Apple has forgotten to take out?
As you said, FaceTime for Mac only started shipping built-in with macOS Lion 10.7, whereas the FaceTime app on the Mac App Store runs on macOS Snow Leopard 10.6.8 (which does not have it built-in).

The Mac App Store download allows customers unable/unwilling to upgrade past Snow Leopard to FaceTime with Mac users on 10.7 or newer, or those on iOS.

As to why Apple does not tick it off for you, it’s simply that this isn’t exactly the same app that ships with 10.7 and above. Case in point, you can’t easily uninstall the FaceTime app that ships built-in, but you could uninstall the one from the App Store, just as easily as you’d uninstall any other app. The version from the App Store also hasn’t been updated in years, as evidenced in your screenshot.