[rcoveson]

I don't think the guarantees you've numbered 1, 2, or 3 are true. Insofar as the package uses the standard mechanism for installing files, sure, it can guarantee that. But I don't believe it hooks a tracer up to the installer script to detect the betrayal of those guarantees. I think it just runs the install script, as root, trusting that the files list and uninstall scripts will do their job. The whole thing is based on implicit trust of the package maintainer, not guarantees in software.

[danudey]

You're right, and I've called that out in my post as well (re: Oracle Java, as an example).

That said, I've got far more trust in someone who's gone to the trouble of making a .deb file than someone who put a shell script on GitHub.