The massive dump-trucks and drill rigs are going autonomous, with anywhere between 10% and 100% (depending on the site) of the heavy vehicles are now driverless.
The routes can be easily predefined, they are relatively short and you can add additional beacons / markers that make things much easiser.
I think the problem with trains outside of say closed loop underground trains that you have a lot of tracks in varying conditions, you can have track abstractions you have a multi agent environment with crossing and that at least as far as cargo trains go the engineer does more than just drive the train they handle many more operations.
Mine site are open cast, mine large tonnage and have long mine lives justifying the large initial investment.
Australian mining operations are also very dry, which helps a lot. Rain introduces a lot of variables.
Large scale automation is particular to the Australian mining industry at this point.
South African deep level gold mines have been working on this for many years with little success, and I think they have mostly given up.