Comment by d0lphin

What's weird, and I'm not sure if it's a documented or undocumented feature, but the account I am logged into on the App Store differs from the one logged into on the system. The system Apple ID is setup with Family Sharing, and the users are able to use apps purchased with the secondary Apple ID.

I haven't transferred the purchases or anything either. The two Apple IDs have different purchases on them, and those on Family Sharing are able to access both.