Earlier quoted context omitted.
It's mostly about age. Python has been around for 35 years now. The first version of a Python package directory was the cheeseshop (Monthy Python reference) in 2003. The earliest version of a pip-like tool was "easy_install" which - I kid you not - worked by scraping the HTML listing page of the cheeseshop and downloading zip files linked from that! More recent languages like Node.js and Rust and Go all got to create…
35 years is misleading. Python existed, yes, but was very different. e.g. Pandas was released in 2008. Most use packages much more recent than that. 35 years ago Perl was faster than Python and had deep adoption (through 2007? or so)
The question is why Python packaging has such a complicated history. The age of the language is entirely relevant to that - the reason Go and Rust have it so good here is that they are much younger, coming out after may of the initial packaging lessons had been learned elsewhere.