Huh Grant, only now I realize your question was more sophisticated... sorry mate, didn't mean to be simplistic. Now that you point that out, I have never seen those right side greeblies in screen captures.
I think I always gave it for granted. I remember people mentioning that there was a resin cast of a screen used ROJ blaster that had those - and I have seen pics of that in the years - , so I always gave it for granted, but you make a good point.