Game industry would be one source. At least for many teams and projects, Git isn't very useful (horrible for large binary files common in AAA games). So many companies still use Perforce or sometimes you'll see SVN still. That means a whole bunch of really qualified engineers who have never or rarely used git.

I'm sure there are other industries for which that is true too.

It's a good reminder how small a section of the tech industry comments on Hacker News.