conda seems to spend a lot of time in a SAT solver or something to deal with the known NP-complete problem of dependency resolution [1]. Maybe pip doesn't do the same thing for requirements.txt setups?
Pip, on the other hand, often "wins" by not even bothering to notice the versions of low-level libraries, etc. If that doesn't work, you get to keep both pieces.
[1] https://github.com/pypa/pip/issues/988
[2] https://pyfound.blogspot.com/2019/11/seeking-developers-for-...