The oil crisis has not only caused petrol prices to soar, it has revealed just how little competition there is among the big oil companies. A couple weeks ago the ACCC announced that it would be looking into uncompetitive behaviour by petrol companies in the rural areas.
The article shows how petrol price rises have been affected in different parts of Australia.
https://thepoint.com.au/news/260327-petrol-prices-are-soaring-in-sync-collusion-or-coincidence
Other cities do, they just don’t show on this graph. You can normally track them on the ACCC’s website. Perth having a cycle isn’t unusual, but it is unusually short and extremely consistent compared to those of other cities.