Been that way since I've been cruising from 2012. So not a recent change at all. Note these are for cruises departing from Australian or NZ ports for Princess, Carnival Australia, PO Australia cruises. All have AUD.
Celebrity and Royal Carribean, HAL, Norweign charge USD on board. Hence why I tend not to cruise with these lines out of NZ/Australian ports. Cause it makesa difference.