Echoing the above, and having driven a real train (well class 58 unit) around a large east midlands depot (a relative who was fairly senior organised it so I got to do the initial class checkout training for an afternoon) it's a crap load harder than you probably think it is. They really are complicated machines with a lot to learn and driving them is a skill that isn't something that easy to master.
The simulators, particularly MSTS is a pretty good representation and a good challenge. Go try it :) Better than running swearing 12 year olds off the track on Forza.
As point of interest, why is it that hard? What makes the task (or mundane parts of it) less automat-able than driving cars (which I think most people would say isn't all that difficult)?
It's definitely automatable, entirely. The DLR in the UK proved that. But that isn't going to happen when the problem is slightly more complicated and not predictable like it is in older lines. You have ot build with automation in mind. One tree on the line and an automated train will plough through it for example derailing it and killing many people ( http://www.caerphillyobserver.co.uk/wp-content/uploads/2013/... ) . One dodgy point, it won't notice and won't report it and the next thing you know, the train is going sideways down a platform side-swiping people ( http://www.virginmedia.com/images/potters-bar-crash-431x300.... )
Machines are shit at noticing these things.
Also the problem is that it's not just about sitting there and pulling a lever - that bit is quite easy. There are a load of surrounding tasks like checking out the locomotives, coupling, shunting, safety rules, signalling, token exchange (which is still used), diagnosing problems (why aren't the brakes releasing can be an hour to diagnose/fix) and the inevitable "managing drunken passengers and coordinating with police" etc.
Not everything is suitable for the lowest common denominator of person or automation.
Given these are the kind of obstacles a Google driverless car has to navigate around, machines may be at the point they can match humans here. Of course this is a much more fancy, expensive level of automation than the "docklands light railway" type.
If a driverless car goes wrong, it's very unlikely to kill more than a double-handful of people.
A 5000-ton freight train capable of barreling along at 100km/h while carrying 50 tanks of propane or anhydrous ammonia or similar is an entirely different risk case ...
The simulators, particularly MSTS is a pretty good representation and a good challenge. Go try it :) Better than running swearing 12 year olds off the track on Forza.