The law has been passed but the actual regulations are to come.

It seems this is more about Meta not wanting to be subject to laws or courts of other countries.

The Australian version of the law would have given the minister power to designate firms, this one requires a more transparent process under regulation that would determine which firms are subject to the tax.

Some observers say that this was key point for Meta because it doesn’t want to accept being subject to legislation by any country outside the US on any issue.

Legislation that uses designations by ministers or Cabinet have been an issue for Canada in the past in trade relations with other countries. Foreign investment reviews. These were claimed to be not transparent decision processes.

What evidence do we have that this is about not wanting to accept Canada having legal authority?

There have been cases where Canadian courts have made court orders on Meta and Google and they have not complied because they claim the Canadian courts do not have jurisdiction. They claim they are only subject to the law of California and the US. As examples, there have been cases where Canadian courts have ordered access to the Facebook and Google accounts of deceased persons and they have not complied.