Come on, autonomous trains are not even generally accepted (no, the Gatwick shuttle doesn't count)...
You'd be surprised - and no they are not limited to airport shuttles. One of the big bottlenecks for autonomous trains is the train drivers unions have fought (successfully) to keep their jobs, even when they aren't actually in control of the train. If they can't get rid of the engineer, there isn't much incentive to spend the money for autonomous control.
BTW, late last year, there was a passenger trail derailment between Seattle and Portland when the engineer took a 35 mph curve at nearly 80 mph. Several people died. They were planning to install an automatic train speed control (that would have automatically slowed the train and prevented the derailment) - but hadn't gotten around to it yet. The public outcry was such that they had to promise to implement the automatic speed control before restarting the route...