Most of them? Ruby gems have hooks, Python has setup.py, deb, rpm have them too (relevant if you're installing from 3rd party sources). Elixir/Mix doesn't technically execute code on install, but your language server builds the dependencies as soon as you open the project, which can execute arbitrary code.

Either way it misses the point, nobody just fetches code and removing post-install scripts wouldn't change much because you're going to run `npm run something` 5 seconds after you run `npm install`.

Python does too I believe.

Really the reason not to allow that is for robustness, not security. You ideally don't want package installs doing random stuff to your system because package authors are generally bad at doing that sort of thing cleanly.

The security impact is relatively minimal because as other people have said, you just installed a package. What's the very next thing you're going to do? Compile/run it obviously.