I didn't even know it had happened. I can't say.
But if I was to speculate ... The ACMA effectively killed email spam originating from Australian businesses years (decades?) ago. The government passed legislation allowing ACMA to impose big fines on companies that sent spam, they then set set up a web form you could upload spam emails to, and a couple of years later there was no email spam ... from Australia. It didn't reduce email spam much, as most spam originated outside of Australia. The other possible choke point was email Inbox suppliers like Google and Hotmail, but they are also located outside of Australia, beyond the ACMA's reach. Still, it did mean when I set up an email / web server for a local club, if I black listed most of the world's IP addresses outside of Australia, it killed all email spam.
The question in my mind was: if they could do it for email, why couldn't they do it for phones after years of trying? They had stopped Australian business from sending phone spam of course, so it all came from internationals just as with email. But this time they did have jurisdiction over the equivalent of the "inbox providers" - the Australia telco's. Most of the overseas spam did come from Australia phone numbers. If it didn't people would just ignore it.
I can only guess those telco's fought the good fight to be allowed to send and charge for spam successfully for a long time. I don't know why they were successful in that fight for as long as they were, but the timing does look suggestive. The USA equivalent of the Republicans run the place federally during most of that time. Now, partly due to example set by Trump, they lost in a landslide to our equivalent of Democrats. These "Democrats" won three years ago too, but now they look to moving as if they have a mandate to do whatever they want.
While this mob speaks in woke tones, there looks to be an iron will fist behind their "kind" words. They are getting the ACMA(?) to enforce age verification scheme internet access for example, something I think is worse than a waste of time. But they are hard and determined taskmasters, so they may make it stick.