As much as I love to rag on things, I would go so far as to say that the big problem with Python packaging is the fact that it tries to manage C/C++ packaging and integration.

If Python is only managing Python code, the issues to be solved are VASTLY simpler. Just about anything works.

Once it has to deal with dynamic libraries, compiled code, plugins, build systems, etc. the combinatorial explosion just makes life suck.

Python is a victim of its own success and versatility.

It has become a better "glue code to solve your problem" than many other solutions and so people want to use it everywhere for everything.

It gets packaged in many different ways because it gets used in many different ways for many different purposes.

Packaging is a difficult problem and all attempts to simplify things fail to understand how complex the problem is and so fail in some way. (Attempts like .deb do okay by only focusing on a subset of the problem)

[delayed]

You forgot about egg!