MacOS also requires superiser privileges to write outside of home directory. Indeed, current MacOS versions do not allow any changes to system directories at al

MacOS also requires superiser privileges to write outside of home directory. Indeed, current MacOS versions do not allow any changes to system directories at all, at least not without changing an obscure setting in an obscure way. Homebrew is an exception, but that's because Homebrew is an abomination. A better answer to this question is that Linux package managers are somewhat primitive and require that any package be installed system wide. On the other hand, it is easy for the unprivileged Mac user to install software to her own directories because Mac application bundles make this easy.