Australia does not supply its own carrier in this scenario because its government had shown little interest in acquiring one before the war. Britain tried a couple of times in 1938 to encourage Australian carrier interest without success. The alternate ABDA carrier core therefore still has to come from the Royal Navy and US Navy rather than from a latent Australian program. Australian naval strength enters the coalition through its surface ships and regional support instead.
Notable Point · 1:24:13-1:24:29
Why Australia contributes no carrier of its own
British efforts in 1938 did not create Australian interest in acquiring a carrier before the Pacific crisis.