Well TBF OP is more or less correct, and I say this as a person who is pretty much into trains (although not train sims specifically). All a conductor can do is accelerate and brake - respect speed limits, brake in time so you don't overrun the platform at the next station (for passenger trains), be on the lookout for people/vehicles crossing the tracks illegally (and hope that they get out of the way fast enough, because once you see them, it's usually too late to stop in time, unless the train is really slow), be careful (especially when you have a freight train) not to be too slow before an incline, otherwise you might not make it all the way up etc. etc. Where you go is not your decision, the points are set remotely.

Just my experience from being on trains, they accelerate, cruise, slow down and stop am I missing anything? They must be ripe for automation.