While Australia’s rate-hike seems to do with their exchange rate and bringing them inline with US pricing (they were paying $11 USD, now it’s closer to $15 USD), the rate-hike for Canada seem more to do with a new tax on digital goods and services being implemented there. Blizz is just passing on the tax that Canada has decided to implement which is what Netflix, Amazon, and other “digital goods” providers will likely do as well.
https://www.cbc.ca/news/business/digital-services-tax-1.5824766
P.S. I just read this in Blizzard’s sticky post: “Please note that currently, the CAD pricing to purchase WoW subscriptions and WoW Tokens will be unaffected by this price change.” Interesting that recurring subs do not get hit, but one-time purchases of game-time are increased. Must be a loophole in the digital tax code?