It's also telling that Google and Microsoft aren't in opposition to this new burden, they're giving quiet yet full support. This will *necessarily* entrench the big players through the burden to implement, make it easier to track individuals across different accounts and services, and endanger the privacy and anonymity of all adults in Australia. And I think that's all the goal.
If they cared about protecting kids they'd focus on resources and campaigns to educate parents on using parental controls. Then parents could decide if they care to block these things in their homes. It should be up to them.
The "you can just log out" loophole, that's just boiling the frog slowly. It would be foolish to think that will stay around.