That's a neat idea, I can see how it'd be useful.

If you have a shell that supports extended globbing, you could do something like:

  $ git who table */**/*.go

That works for me using Bash. I believe all that's happening here is that Bash is expanding the globs and passing a long list of individual filepaths as arguments to git who. Git who then passes them to git log so that it only tallies the commits you'd get by running:

  $ git log */**/*.go