I'm not even sure it is compliance at all. I'm under the impression that Australia's age verification laws require multiple options such that no adult is left blocked with no recourse.

I cancelled my credit card a couple of years ago. So I suppose I'm out of luck. Not that I care much, because I've highly unlikely to want to buy an R18+ game on steam anyway. It still sucks though.

My Steam account itself is more than 18 years old, so it's pretty absurd to assume that I might be somehow underage...