I think at least part of it is that there are so many solutions for Python packaging, which are often intermixed or only half-supported by developers. It's a tough ask to provide dedicated support for pip, conda, poetry and what else is there plus a couple different ways to create virtual environments. Of course if you do everything right, you set it up once (if even that) and it just keeps working forever, but it is never like that. Someone will use a tool you haven't and it will not work correctly and they will find a workaround and the mess starts.
Also I think that Python packages are sometimes distributed as shared libraries is a problem. When I think about conan or vcpkg (package managers for C and C++), they usually suck because some dependencies are available on some platforms and not on others or even in one version on one platform and in another version on another and you get messes all around if you need to support multiple platforms.
I think generally binary package managers are almost always bad* and source based package managers almost always work well (I think those are essentially easy mode).
*: unless they maintain a source package of their own that they actually support and have a fixed set of well-supported platforms (like system package managers on most Linux distros do).
The problem is a lot of Python source is actually a C/C++ file, so simply having "source based package manager for Python" is very annoying, as you'd have to manage your C/C++ sources with some other mechanisms.
This is exactly the reason I've moved from pip to conda for some projects: "pip" was acting a source-based package manager, and thus asking for C tools, libraries and dev headers to be installed - but not providing them as they were non-Python and thus declared out of scope. Especially on older Linux distributions, getting dependencies right can be quite a task.
This used to be a big headache for me, especially having developers on Windows but deployment targets in Linux, but a lot of the libraries I commonly use these days are either pure python or ship wheels for the platforms I use.
Were your issues recent or from several years ago?
The issues were recent (as of few months ago), but the OS's were pretty old - Ubuntu 20.04 and even 18.04. Those are still officially supported with Ubuntu Pro (free for individuals), but have ancient libraries and Python versions.
Also I think that Python packages are sometimes distributed as shared libraries is a problem. When I think about conan or vcpkg (package managers for C and C++), they usually suck because some dependencies are available on some platforms and not on others or even in one version on one platform and in another version on another and you get messes all around if you need to support multiple platforms.
I think generally binary package managers are almost always bad* and source based package managers almost always work well (I think those are essentially easy mode).
*: unless they maintain a source package of their own that they actually support and have a fixed set of well-supported platforms (like system package managers on most Linux distros do).