And it does, for most languages. Python seems more difficult than average.

Yea python is the exception. Go, rust, nodejs, have been easy to get running with specific versions and dev envs .

...and yet there's tons of Python packaged in traditional distributions including Django.

So it's not clear what the real benefit of Nix is.

Nix hasn't been a benefit when working with python for me, but again, python is the outlier. It has been a benefit for projects in other languages.

I guess the reason is because python packaging/tooling varies wildly between projects, and there are a lot of bindings.

BTW a colleague was setting up the python project on a non-nix machine, and also had problems with dependencies, and ultimately had to do some nasty workarounds (disabling deps/features). To me, it seems endemic.

There's plenty of python packaged in nixpkgs too. It doesn't mean that it isn't a dumpster fire disaster. Dealing with it has been trouble with every other distro I've used. It isn't just a nix problem. If anything I think the situation is improved.

It does. Nix can package everything properly. What is depending on the language ecosystem in question is whether this packaging can be more automized or not.

Python is not trivially automatized with Nix.