It is a requirement to work on a construction site in Australia. In each state the cards may be a bit different, in Victoria I believe its red card, in NSW its a white card but we call it a green card... because it used to be green. But whatever card you can use it all over Australia.
For about $100 you go to a workcover registered training company and they induct you on safety and give you a quiz at the end.
The whole process takes about five hours. Unlike the licences to be a dogman or crane operator which you will fail without study, no one fails the green card.
So if you are a worker from overseas or want to start new in construction the green card is the first step.
It wont get you a job but without it you wont get a job