From my personal experience, there's so many things that can crop up, not limited to:
- Conflicts with system packages from e.g. apt
- Conflicts with system packages from easy_install/pip
- Mismatching Python versions (even among 3.x with syntax additions only available in newer versions)
- Different dependency management systems (pip's requirements.txt, setuptools's setup.py, poetry's pyproject.toml, etc.)
- ... and the list goes on if you start talking about C extensions!
Additionally, not everyone does things in the same way which means the easiest way to package Python tools tends to be just bundling Python + its entire standard library together. Contrast this with Go, where `go install` does basically the right thing 9 times out of 10. I'm not a huge Go fan, but the convenience of `go install` is really unmatched.