For that matter, IMX much of what people praise uv for is simply stuff that pip (and venv) can now do that it couldn't back when they gave up on pip. Which in turn has become possible because of several ecosystem standards (defined across many PEPs) and increasing awareness and adoption of those standards.

The "install things that have complex non-Python dependencies using pip" story is much better than several years ago, because of things like pip gaining a new resolver in 2020, but in large part simply because it's now much more likely that the package you want offers a pre-built wheel (and that its dependencies also do). A decade ago, it was common enough that you'd be stuck with source packages even for pure-Python projects, which forced pip to build a wheel locally first (https://pradyunsg.me/blog/2022/12/31/wheels-are-faster-pure-...).

Another important change is that for wheels on PyPI the installer can now obtain separate .metadata files, so it can learn what the transitive dependencies are for a given version of a given project from a small plain-text file rather than having to speculatively download the entire wheel and unpack the METADATA file from it. (This is also possible for source distributions that include PKG-INFO, but they aren't forced to do so, and a source distribution's metadata is allowed to have "dynamic" dependencies that aren't known until the wheel is built (worst case) or a special metadata-only build hook is run (requires additional effort for the build system to support and the developer to implement)).