[pdw]

And Mac copied it from Xerox. But it was indeed the introduction of GUIs and WYSIWYG "what you see is what you get": the screen had to mimic paper.

[tempest_]

It didn't have to though.

Lotus 1-2-3 mimicked a spreadsheet and it is not searing white.

[seanhunter]

...and Lotus 1-2-3 mimiced visicalc and when I used visicalc (on an HP85a) it had a dark background with a greyish white foreground colour. ie dark mode by default.