"Australia" doesn't really set records, multinational mining companies do. The records might as well be set on another planet. There is virtually no population, roads or utilities, no agricultural land beyond low density cattle stations that need up to 50 hectares per head, no mountain ranges, no large rivers, and employing people to work on site out there is might be 3x more expensive than the rest of the economy. The records are set on private lines that operate outside normal rail regulations by agreement set down by state governments that are beholden to the mining companies.

Comparing USA's freight rail network to Australia's on those numbers paints a misleading picture. 3/4 of it is iron ore and coal being carried relatively short distances (few 100s of km) from inland out to the nearest coastal port, and most of that is away from any significant population centers.

By ton-mile, USA takes 5-6x more than Australia and much more interesting and varied conditions and freight types and destinations - not just ferrying it from a hole in the ground, across highway 1, then into a bunker at a shipping terminal.