If the earth pin is not optional, how do you plug something in if it isn't present? Do you have special sockets for devices that are double insulated?
I mean not optional by certification and law, not physically, so no, we don’t have different sockets - all sockets have earth, but it doesn’t have a shuttering system like the UK’s.
A two pin plug still plugs into a regular socket, it’s just illegal to produce or sell something without an earth pin if it doesn’t meet safety standards for double insulation.
I'm not sure what you mean about plugging it at a slightly wrong angle, I haven't experienced that (in ~25 years of using Australia plugs).