The first time I discovered that "dragging an icon to the trash" was one of the few ways to uninstall an application on Mac, my mind was a bit blown. I was struggling so hard to find an "Add/remove programs" equivalent or an uninstaller.
And that also prompted me to confirm that it would delete the proxy and the Extensions that were installed.
I remember a few more apps being like that. So there ARE hooks, just not used universally. AND it won't delete personal files or preferences related to the app, which is what users are expecting these days when they delete an app, UNLESS it's an app installed from the App Store, because those store prefs and data in a different folder than regular apps..
I would be interested if someone could point me to the mechanism used for that (triggering application-specific uninstall logic upon dragging the application to the trash).