This is a hell of a comparison to try to make. How many people do you think regularly run into this kind of issue in Postgres? How many people do you think regularly run into the Python GIL?

Even if we assume your premise that vacuum is at least as bad as the GIL is correct, this would easily explain it.

Add in the sheer difference in expectations between a programming language and a database... and well, I don't think there's any mystery here at all. There's easily multiple great explanations, even if your premise is correct.