For the leaving files around case, isn't that an impossible thing to really deal with from the installer stand point for non containerized applications that have root/admin access?
Because they can just create and write to random directories whenever they want. And any Uninstaller, either provided by the app or Microsoft could just miss these files, because they aren't recreating the full program control flow.
This is why we invented distributions (Linux and friends): one package manager, common practices and shared code, to avoid everybody doing its own (sometime broken) thing
And now we also have flatpak, snap, etc. on top ofnthe "one package manager"
Why is it impossible if you can track where they write during the installation process? There are even apps that do that. For apps that run as admin that's harder indeed, but at least for the installation process the good-but-not-perfect design could still be added?
Yes. UWP/MSIX+AppContainer addressed this, but inherently impose limitations on what the app and installer can do.