Whats the go with interstate rego

[GREGL]

Interested to know how a car can be driven for a long period of time while being registered interstate. The vehicle in question has been around for 3 yrs and I see it regularly, bloody everywhere in fact. It is a early 70's celica in very average nick, sagging suspension and all.
Registered S.A , how do they get around it? I know through experience that in the past a car if garaged in QLD on a permanent basis had to be transferred to QLD rego after a certain time. Has the law changed?
It really annoys me that some ex pat S.A can use our roads while not contributing a cent to revenue (I read somewhere apparently they don't speed). This one certainly doesn't 0-55 in what seems like a eternity.
Just being a Queenslander an havin' a whinge!