@apples_and_pears For instance, I'm pretty well convinced that the unified UI you saw for full keyboard adder-listers starting in the 1920s had to do with Burroughs dominating the market (and acquiring most big competitors) and the remaining competitors in the market painting their own adder/listers to match the classic Burroughs black case/green felt under the keyboard design from the Model 1 so they could hope to replace Burroughs in some businesses.
@apples_and_pears Ignoring Comptometer, which went their own way, the rest copied the black/green color scheme and full-key layout basically until the post-WWII era when the aesthetic turned toward military greens, shifting to greys in the 50s/60s.