Well pip is only one command, so it can't simultaneously work for both Python 2 and Python 3. And if you happen to have another installation of Python or pip in

Well pip is only one command, so it can't simultaneously work for both Python 2 and Python 3. And if you happen to have another installation of Python or pip in your path (e.g. at the user-level) but not have the other one there, then they'd affect different installations entirely. When you run it via Python you know it's affecting exactly the same installation. Upgrading pip itself is kind of a special case I think. You don't want to upgrade stuff managed by a system package manager using pip; their work will conflict with each other. This includes pip itself. I think this is kind of a mess and I don't know of a great way to deal with it other than just remembering not to upgrading system packages using pip (yes this includes pip itself, and means you should avoid trying to upgrade via --user if it's installed on the system). On Windows where I am it's ironically less annoying since there's no system-level package manager to worry about... go figure.