Except when you install something on linux package manager of your distro is executed as opposed to installer that was made by developer of package you are installing. And you probably install install packages from your distro's repos, unless you are on Debian of course.
Or you can run package manager as user that usually installs in ~/.local. Or unpack yourself.
That's why I use Gentoo. If something breaks I just boot system from external drive and solve the issue. Or even if bootloader breaks I can use kernel from external drive, but boot into main system.