I can't really see too much incentive for Apple Pay in Australia, given that everyone is used to just waving their credit card over the reader anyway. Apple Pay isn't at that much of an advantage given the convenience of contactless payment (which has been commonplace for many years).
The convenience to users is that if you lose your phone, you don't lose your credit card. The number generated is per trasaction. If ANZ also offered ATM access via contactless/Apple Pay you would not need to carry your card with you anymore. Also as the number is a once off, it protects you from fraud or someone copying your credit card details at a retailer/merchant.
The reason banks like it is for similar reasons. Every bank has a call centre that deals with lost/stolen cards and the generating of new cards and sending them out. And investigations of fraudulent transactions
IF you pay with Apple Pay you use your iPhone & fingerprint or an Apple Watch that was unlocked near your phone that had already been authenticated too. Basically the banks know if you purchase via Apple Pay, it is actually you making the purchases.
= less work & more secure for the banks
99% of retailers in Australia support contact less payments.
The banks here own that infrastructure (whoever the retailer banks with supplies the system).
I am sure the sticking point has been the fees Apple charge. Or maybe ANZ actually sat down and worked out for the extra security, it was worth paying the fees Apple was asking...
Anyway I used it before to buy some tickets to the movies after school with the kids. It worked perfectly!