The rules are less about children being barred directly, and more about stopping social media profiting like they once did when they scraped the personal info of kids, used various algorithms to target the large ad revenue from the teenage market with more though on profits and less to the cost of any mental detriment to kids growing up with an invasive online world.
Sure some under 16 Australian kids will still be using social media, but so will those who will report if the big social media companies are openly ignoring and not complying