The PVP Instance you are in can be in any region associated with the players you’re with. This has been a problem for a very long time, and can give you really nasty latency.
Example if you’re in Aus and Q up for BG’s / Arena and then maybe 1 player on the other team is in NA, there is a chance that even tho most of the players are from Aus, that the PVP server could be hosted in NA anyway.
The inverse has also been true, where a single player is from Aus but everyone else is in NA and the server is hosted in Aus giving near everyone terrible latency for PVP use.
Problem is there is no good way to solve this problem for Aus players; if you’re wanting to play VS aus players only and be on local only servers your Q’s for PVP will be longer, but if you want to play with NA players then Latency will be worse frequently.
Until latency free internet exists this will continue to be a problem for gaming world wide; especially in Areas where a game is less popular for its varied reasons.
TL;DR: No good solution presently exists here other than the trade off of Long Q’s for Aus players.