Technology

Plenty of self-driving trains around, generally metros where frequency and 24/7 operation is a great boon to overall service quality -- you don't want people to look at schedules, you want them to go to the station knowing there's going to be a train in a couple of minutes, tops.

It's way different for long-haul service, freight, passenger, doesn't matter. Longer and less frequent trains with way more passengers in them, and you probably need other staff too, like someone needs to run the bistro. The tracks they're running on are also way less predictable, with a metro you can have station screen doors everywhere (which btw necessitate automatic driving, humans aren't accurate enough) try that with an international train: Regions much less countries can't even agree on uniform platform heights. Much less door locations: Automated long-haul would require dedicated platforms at every station and while those could be served by trains with drivers, trains nowadays are all smart enough that including a button "stop at exactly that location, to the half-centimetre" isn't an issue, those trains would have to have doors at the right location. Now go ahead and convince Germany and France that they need to replace all TGVs and ICEs to have doors in the same location as your regional trains.

Oh and none of that automation tech used with trains uses machine learning, btw. At least not at the basic level, when it comes to actually driving the train. I do remember watching a documentary about Singapore's metro, where they have an ML algorithm scheduling track maintenance, minimising not service interruptions as such but impact on people's commute. First the workers complained that none of the orders made any sense, then the developers made the computer spit out context and motivation alongside with the orders, workers changed their tune to "that's fucking brilliant".

...which, actually, brings me to the conclusion: Also with automated systems we're going to need maintenance which isn't going to be automated any time soon. If you automate a metro that currently doesn't run 24/7 you don't have that many drivers in the first place, and probably have other jobs for them to do. Automating really is about making "a train max. every five minutes, 24/7" possible without breaking the bank.

I'm sorry I am not trying to dispute the spirit of your respose but I have to disagree, freight trains are thousands of feet long and haul unbelievably large quantities of material, the idea that it is inefficient to have a human (really a pair of humans) oversee and be responsible for a machine that large is laughable honestly.

...so is the idea that there is a genuine shortage of people willing to work as conductors, it is a convenient lie companies tell to rationalize why nobody wants to work for them because they pay shit and respect their employees so little that they won't even give them unpaid time for necessary doctors appointments (see recent action of US train workers).

This point is even more true for passenger trains.

It is a massive responsibility we can afford to pay two humans to do it, a certain micro amount of inefficiency is ok.