What are the reasons that so many old diesel streamline locomotives are still in use in Australia? They were pretty much phased out of all operational use in North America and I think the only operators left are heritage railways or novelty railways (like...there's on in California that just gives tours of vinyards).

There are still quite a number of both freight and passenger railroads in Australia that are running old 44 classes, GM classes, B classes and so on dating as far back as the 1950s. Now I know North American railways still use engines that old, but for general purpose use they switched to more boxy locomotives.

So why do the Aussies still like to keep them around?