[card_zero]

The 3 with a flat top is a "banker's 3", an anti-forgery measure:

https://en.wikipedia.org/wiki/3

Playing cards use this style of lettering. Not sure how far back that goes but I kind of doubt they all derive from Gorton's specific engraving machines.

[eCa]

And used on eg German license plates, for at least partly that reason (IIUC).

[lencastre]

Down the rabbit hole I go….

[spacechild1]

Ah, that makes sense! Thanks for this insight!