[nilram]

I see discussion that the OP was about headshots for a different frame of reference, but passport/visa photos are an interesting comparable. Every country has their own standard (dimensions, framing, glasses/no glasses, smiling/not, etc). Although they might not vary too much, it used to be easier for an international traveler to go to a "passport photo" shop (as I did, years ago), but now, as you point out, it's a problem that can be solved with a computer.