I took this picture from the Sydney Tower of Fleet Base East and in it you see the 2 Canberra Class Helicopter Platform ships, and you see they have Ski Jumps. This led me to consult Wiki and I see they were constructed to plans used for the Spanish Navy San Juan, (Harrier ) and even though Australia have no plans to operate Harrier or F35b it was cheaper to go with the plans including ski jump, and would have cost more to build with no ski jump
Guess who the builders were?.....Yep Bae