Why so? We don't go into great depth, but every hiring committee I've been on I make sure that we ask something about source control.

You can learn a lot about a developer's process by finding out if and how they use source control. (Red flag, for me, is if an apparent senior dev doesn't use a VCS.)

Red flag = warning sign, not anything related to Git flags.

OJFord is basically correct, though. It's 2020, so if you're interviewing for a developer/programming position, you should at least know something about the various VCS options.

If it helps, during our last set of interviews the question was "What is your strategy when using source control?"

Before that was the two part question of "Describe your preferred development environment, both physical and technical. What is one thing in your development process that you can’t live without?" (I always tell the candidate that my answer to this is some sort of VCS.)

(These were both for the second, in-person, interview. There's not necessarily a wrong answer. It's not like we're asking them to name as many differences between Git and TFS as they can. :) )