> That is me "trying to install other people's scripts" the other people's script is just a little old thing called FreeCAD, no big.

What I don't understand is why you call it a "script".

> and python3 writes _pycache_ directories everywhere a script executes (which means everywhere, including all over the inside of all my git repos, so I have to add _pycache_ to all the .gitignore )

You're expected to do that anyway; it's part of the standard "Python project" .gitignore files offered by many sources (including GitHub).

But you mean that the repo contains plugins that FreeCAD will import? Because otherwise I can't fathom why it's executing .py files that are within your repo.

Anyway, this seems like a very tangential rant. And this is essentially the same thing as Java producing .class files; I can't say I run into a lot of people who are this bothered by it.