The practical answer is that cartography started in the northern hemisphere, and it was just a natural format. The technical answer is that the magnetic north pole was recognised very early in navigation and reflected in cartography.
But there is NO SINGLE reason why Australia, the world's best country, should not be on top of the world. To demonstrate this, I attach MacArthurs universal corrected projection!!!
SW-User Best Comment
The Australian kiss is like the French kiss but “down under” lol