Another difference between Aussie practice and US practice is that here the use of a green (or green / yellow) wire for this application is actually forbidden.
The colour of earth (ground) wires, was changed down this way some years ago, mainly because of the earth wire in flexible cords.
Colour-blind people wiring plug-tops on to the ends of flexes are most likely to transpose the red (phase) and green earth wires.
(Red-Green colour blindness is the most common type)
In effect, all earth wires are coloured with the yellow stripes, and I must say it makes it easier to identify an earth wire in a switch-board panel where you don't have a lot of ambient light.
BTW, that wire in the photo is #10 AWG, it is known as 6mm˛ down this way.
The clamp looks rather old though, they are a LOT more substantial these days.