There's still no real substitute for having a person on site to do work when machines breakdown or get stuck and the problems with trying to use machines in their place get worse as the time lag between the machine and it's operators gets worse. Even on modern automated oil rigs there are people driving, repairing and monitoring the systems locally.

Really we're pretty far from semi-autonomous systems for stuff like mining, we're just starting to get problem solving working in AI just look at the DARPA challenge for how far we are from being able to assign relatively small tasks to resolve problems.