>I've heard many say online that this law is sold as "save the children" but is designed to be used to get everyone to provide ID when they go/public/message online.

Because this was attempted already, for example with the UK "porn ban" law. And Australia is one of the few countries that are even more batshit insane when it comes to policing and controlling its own population, and possibly the only country where such a law could pass now.