It's still not entirely clear how the Australian government thinks they're actually going to enforce this.
Plenty of web services already require you to state your age to use them and I believe a large majority of users just coincidentally happen to be born on January 1st, 1900 as a result.
If they're expecting these tech companies to be gathering and storing peoples' government ID's, or something, somebody needs to carefully explain to them using small words why this is a monumentally stupid idea. Does something need to be done about social media addiction and the rampant sketchy behavior of the tech giants? Yes, probably. Is a blanket ban ever the actual solution to anything? No, very rarely.
It's just apparently all anyone can come up with when they've got government-brain.