I have no idea, but I do have a PC/AT keyboard with similarly-shaped keys. They have the usual "square horseshoe" / "anti-roll bar for Matchbox cars" arrangemen

I have no idea, but I do have a PC/AT keyboard with similarly-shaped keys. They have the usual "square horseshoe" / "anti-roll bar for Matchbox cars" arrangement underneath so they don't rock when you press the end. I think it's just what they did in the 80s.