One question (I didn't read the article, but it just popped in my mind while thinking of driverless trucks). Is anyone working on driverless trains? If not, wh

One question (I didn't read the article, but it just popped in my mind while thinking of driverless trucks). Is anyone working on driverless trains? If not, why not? I understand that the impact would be less huge, but at the same time the problem domain is arguably more tractable. In my hometown we have a fully automated underground train line which has been working flawlessly (i.e. no accidents) for almost 10 years now, but according to Wikipedia it looks like ATO (Automatic Train Operation: https://en.wikipedia.org/wiki/Automatic_train_operation https://en.wikipedia.org/wiki/Automatic_train_operation) is currently deployed only for urban transport, while proper railways, even the Japanese ones, seems to use only ATC (https://en.wikipedia.org/wiki/Automatic_train_control https://en.wikipedia.org/wiki/Automatic_train_control) which from what I understand provides support to a human driver but still needs one to operate. (edit: typos)