pip is a perfectly usable package manager and is included in most python distributions now. Is it perfect? No, but it is good enough for every team I have been on.
Putting aside the speed uv has a bunch of features that usually require 2-4 separate tools. These tools are very popular but not very well liked. The fact these tools are so popular proves that pip is not sufficient for many use cases. Other languages have a single tool (e.g. cargo) that are very well liked.
We do geodata science and rely on some pretty specific C++ libraries that are only distributed via conda. While on unix-based systems it's possible to get some of them from other channels or even building them from source, we mostly have Windows machines in production where we are not that flexible. Docker is unfortunately no solution due to security concerns.
If you are asking why I hate it: It's bloated, uses more space than needed and it's rare I can reproduce an environment from the environment file without running into errors. Using it feels unintuitive, I still google command after years. It was very slow until recently, when the libmamba solver was finally integrated. Last but not least licensing is a pain in the ass.
They have a --dev shorthand for dev dependencies, but it seems the dependency group PEP is not final, so there isn't a standardized way of doing this yet.