can you point to a minimal example where vanilla vim autoindent cannot cope with python code editing? I never found any situation where I had to press the tab key

Have you ever refactored anything? Especially in Python, moving a line into a control block requires using the tab key. If you don't have to press the tab key either you're such a god programmer that you have never made a mistake or refactored anything you've ever written, or you're trolling.

there's >> and << for changing the indentation of a line.

And i'm not a good programmer, a good vim user at most