>GM and Ford had no problem extracting itself from Australia,

The only thing they extracted were their manufacturing operations, GM and Ford still sell vehicles in Australia. They even have the Focus which Ford dropped for the American market! Unless Google and Facebook are going to close their offices but still provide service to Australia, that seems like an entirely different scenario.

GM will effectively end sales once they wind down the Holden brand over the next year.

They killed off Holden but they're still selling some Chevrolet models, and there have been a lot of Cadillac test mules spotted around Australia.

https://www.goauto.com.au/news/cadillac/spied-cadillac-ct5-p...

https://www.goauto.com.au/news/holden/gm-has-lsquo-a-future-...

They can certainly do that. It would mean Australian firms would need to buy ads through a foreign broker or sibling company, but many Australian advertisers would have those sorts of firms in existence already.

car manufacturers leave expensive countries because there's an opportunity cost. If they can move their infrastructure from Australia to Thailand they make more money. Google already is everywhere. When they leave a country they just lose money. The marginal cost of production for large tech companies is close to zero so leaving a market virtually never makes any sense. Which is of course why all of the tech companies would personally grovel in front of the CCP if they let them in regardless under which conditions.