And other social media?
Always easy with Facebook, Instagram, X, etc as the government can fine them. So what happens with decentralised Mastodon, Friendica, Diaspora, Peertube, etc where there are hundreds of servers all over the world - the legal accountability here is being placed on the hosting party. With Peer to Peer networks it gets even more complicated as there is no central hosting service at all - think of Nostr, SSB, RetroShare, Aether, etc - your own computer or phone is the host.
The world has changed, and I'm still interested to see how brands and governments are going to catch up. Many kids today have no interest in these legacy platforms apart from maybe TikTok, but decentralised Loops has just launched as an alternative to TikTok.
If proof of age over 16 is going to mean having to produce government IDs to prove that to each and every network, I see a major privacy risk as there is no way that information can be kept safe anywhere online.
Kids will go where they can, so I really don't think parents can just sit back and abdicate their role. Of course, with Australia, they could just add a gov warning sign on every lawn outside houses where kids live. I gather the warning signs are quite a big thing.