In Australia, the government spends over $70B on healthcare, but collects only around $10B through Medicare levy surcharge. The only reason your healthcare spending in Australia seemed so low is because an overwhelming majority of the cost of healthcare in Australia is covered through general taxes, and not through the Medicare tax. Even if you focus on Medicare benefits only, the Medicare levy surcharge only covers less than half of the Medicare benefits.

That said, healthcare in Australia in fact is cheaper than in the US, but not as much cheaper as you think it is.