I'm going to assume you are talking about rpm and deb packages since they are still currently the dominant installation packages on Linux.
> Define a separate directory for program installations, that user processes cannot write to. Only program that can do so is the package manager, which other programs can call to install packages.
Windows does this. Programs are installed in directories under "C:\Program Files" which is only writable with elevated system rights.
> Uninstall removes everything related to a program from this directory.
rpm and debs don't install all the files needed for a program in a single directory. They are scattershot all over the file system and in many of these directories comingled with files from other programs. Windows comes closer than Linux in this regard since it does create the directory under "C:\Progtam Files" which while unfortunately doesn't always contain all the required files usually contains the vast majority.
I'm going to assume you are talking about rpm and deb packages since they are still currently the dominant installation packages on Linux.
> Define a separate directory for program installations, that user processes cannot write to. Only program that can do so is the package manager, which other programs can call to install packages.
Windows does this. Programs are installed in directories under "C:\Program Files" which is only writable with elevated system rights.
> Uninstall removes everything related to a program from this directory.
rpm and debs don't install all the files needed for a program in a single directory. They are scattershot all over the file system and in many of these directories comingled with files from other programs. Windows comes closer than Linux in this regard since it does create the directory under "C:\Progtam Files" which while unfortunately doesn't always contain all the required files usually contains the vast majority.