Well the metric you replied to was rail network size, and was correct about the USA having the largest. "Rail performance" would more typically be measured by ton miles or tonne miles, not "tonnage". Australia still does a bit better there per capita there.

But in either case it is almost entirely these isolated short private coal and ore export lines that have no interconnection or interaction with the rest of the country's freight nor does it remove freight from any roads that the rest of the population would be using. These are virtually entirely in isolation from the rest of the country or economy or transport network and are built by and for mining multinationals. In the context of a country's governance or transport infrastructure or general rail networks, they don't say anything. If they were there or not there or private road and oversize road trains instead, it would not change anything about the rest of the country's transport.