The first is for system-wide apps, the second for apps that the user doesn’t share with others, the third for some parts of the OS itself. It would be insane to

The first is for system-wide apps, the second for apps that the user doesn’t share with others, the third for some parts of the OS itself. It would be insane to throw all that in one place. Similarly, yes, getting app info involves parsing files in a known location with a known format, how could that situation be better? I’m not sure how often people fail to put applications where they go. Especially nowadays, where most applications ship as .dmg files that open to a giant arrow telling you to drag the app to Applications, and many nag you if they’re run while not there, and App Store solves this entirely by just putting them there.