[franky47]

My AZERTY keyboard conveniently has them side by side (^ left of $).

Could it be a similar reason?

[jcranmer]

AZERTY is primarily a French keyboard layout, to my knowledge.

The standard QWERTY layout for the number key row is `/~, 1/!, 2/@, 3/#, 4/$, 5/%, 6/^, 7/&, 8/*, 9/(, 0/), -/_, =/+. I don't know how far back the mapping of shift keys for the numbers go, but I'd be shocked if there was any around the 1960s or 1970s that put them like your AZERTY keyboard.

[dfox]

During the relevant time there were two predominant layouts for the number key row: “typewriter-paired”, which is more or less same as the one used today and “bit-paired” where the symbols had the same order as they have in ASCII (ie. pressing a number key while holding shift produces a character represented by that number's ascii codepoint minus 0x10)

[franky47]

Yes (I am French). Those characters are found on the top letter row: AZERTYUIOP^$

[hwayne]

I think this is unlikely, as the three people involved (Deustch, Lampson, and Thompson) are all American.

[amelius]

Exactly what I thought of, but on querty it is the other way around.