uv not only completely replaces all of pip, pyenv & venv, but it also does a much better job than any of them at their intended function, as well as a bunch of other convenient, simple developer-friendly features.

1. pip isn't entirely to blame for all of Python's bad package management - distutils & setuptools gave us setup.py shenanigans - but either way, UV does away with that in favour of a modern, consistent, declarative, parseable PEP 508 manifest spec, along with their own well-designed lockfile (there was no accepted lockfile PEP at the time UV was created - since PEP 715 has become accepted UV has added support, though that PEP is still limited so there's more work to do here).

2. pyenv works fine but uv is faster & adds some nice extra features with uvx

3. venv has always been a pain - ensuring you're always in the right venv, shell support, etc. uv handles this invisibly & automatically - because it's one tool you don't need to worry about running pip in the right venv or whatever.