Sydney is not even close to being a world class facility.
What is world class when it comes to airports? Sydney airport certainly has its issues but plenty of major cities around the world have airports with significant issues too.
LHR has been too small for decades and I’ve suffered more delays in and out of there than SYD.
NRT until not that long ago could not even acquire the land to build two full length runways and a proper taxiway system.
LAX has plenty of runways but the terminals are horrendous.
JFK is has been operating beyond its capacity for decades
AKL’s second runway is a taxiway???
BKK built a brand new airport that sunk, cracked and terminal overheated.
I could go on and on.
I’ve not done a lot of international flying these last few years so some of these issues may have been improved. But my point is that having terrible airport infrastructure seems to be a common trait of world class cities.