I agree that testing for knowledge of specific tools is probably not what you want, but I find that among people who do have significant experience with git, ability to use it effectively seems to correlate pretty strongly with overall programming ability and productivity.

I mainly have experience with git, but I assume this generalizes to other version control systems. I also think that version control is a pretty fundamental skill for software engineers (comparable to unit testing), so I think substituting that for "use a version control system to do x" would fit in with with other skills.

I would disagree when it's a clear requirement of the work to be done (and often tossed haphazardly onto a resume). There can be some real time sinks that are not towards making someone productive in a code base as you have to stop and teach them how to think about Git. There's also the fun of having to use advanced Git magic to untangle their PR into something sensible because they've done odd merges along the way where they should have rebased their commits. People that still are from centralized source control only world still exist and getting them to work Git well is a skill that's worth interviewing/filtering over if it's a day 0 expectation.