> Ctrl on the Mac started as Terminal-Emulator specific modifier
It did, but when starting history with the first Mac, it started as being absent. The Mac initially had shift, command, and option modifiers.
Apple introduced control keys (separate left and right ones) because companies writing terminal emulators needed it.
> Apple introduced control keys (separate left and right ones) because companies writing terminal emulators needed it.
I'm not sure that's the correct reason.
The Apple II/III had the control key from the start. The Mac keyboard originally did not have control (nor escape.) When Apple introduced the external Apple Desktop Bus keyboard designed to be used with both the Apple IIgs and the Mac, it needed the full complement of keys to be used with both systems.
https://en.wikipedia.org/wiki/Apple_keyboards#Discontinued_k...