I have done some searching but can't really find an answer...

If I choose to fly to NZ and transit at SYD in both ways, there are no taxes or fee what so ever going thru Australia.

However if I choose to have a stopover at SYD on my return. Understandably, there are going to be some fee. I see a (AU) Australian Passenger Movement Charge for C$59.10. That's fine. But also 2x (WY) Australian Int'l Passenger Service Charge at C$27.90ea.

Any idea what's this WY is? Is it because I get ding once for coming from NZ into AU. And ding again for leaving AU to go home?

I only find a doc talks about (AU) Australian Passenger Movement Charge Exemptions (here) but noting (so far) I can find on (WY) Australian Int'l Passenger Service Charge...