SYDNEY  -  Social media companies could be fined more than US$30 million if they fail to keep children off their platforms, under new laws tabled before Australia’s parliament Thursday.  The legislation would force social media firms to take steps to prevent those under 16 years of age from accessing platforms such as X, TikTok, Facebook and Instagram.  Failing to do so would mean fines of up to Aus$50 million (US$32.5 million).  Australia is among the vanguard of nations trying to clean up social media, and the proposed age limit would be among the world’s strictest measures aimed at children. Details about how social media companies are expected to enforce the ban remain unclear.  The proposed laws would also include robust privacy provisions that require tech platforms to delete any age-verification information collected. Minister for Communications Michelle Rowland said Thursday that social media companies had a responsibility for the “safety and mental health” of Australians.  “The legislation places the onus on social media platforms, not parents or children, to ensure protections are in place,” she said.  Some companies will be granted exemptions from the ban, such as YouTube, which teenagers may need to use for school work or other reasons.  Rowland said that messaging services -- such as WhatsApp -- and online gaming would also be exempt.