Note that it will always be Grade 2 LOA (Level of Automation) which requires a driver to still be present in the drivers cab since the system isn’t designed for Grade 4 LOA (like Sydney Metro) which requires a closed system with platform screen doors, track violation sensors etc.
It would be like London Underground, where the driver starts the train, the ATO then controls the speed and stops at the next station, but the driver can apply the emergency brakes if required.
And I consider this the most dangerous form of automation. The system isn't fully failsafe as they assume a human is supervising. However, said human won't really be paying attention, got to be one of the worlds more boring jobs, being the babysitter for a mostly automated train.
When something does go wrong, precious seconds are lost while the driver/attendant gains 'situational awareness' and takes action. Or they take an inappropriate action in panic.
The airline industry mostly understands this, and despite aircraft having autoland and auto takeoff as well as 'autopilot' cruise control, most takeoffs and landing are done mostly manually - so the crew keep their skill level up - and more importantly, if something does go wrong are full situationally aware. (A flight engineer neighbour once told me if you have a super smooth landing, don't congratulate the pilot, he left the plane in auto-brake
I've been on an ATO train where due to a glass cab wall, I could clearly see the driver reading a book, not looking out for obstructions ahead. Had there been an obstruction, track fault, misaligned switch, there is no way that guy would have noticed in time to stop the train before impact.
I would assume if they pull off the Grade 2 implementation, after a few years the trains will gain LIDAR/RADAR sensing units for obstruction detection and the system will migrate to LOA 4.
Rio Tinto is (or will be) running huge unit ore trains with no driver on board. One of the reasons for the project in the first place was the difficulty of recruiting drivers and one of the main delay factors to trains was lack of crew. They may still have a supervising driver at this stage, but the endgame is clear - no one on board. The sensing technology deployed for that project will make its way back into urban rail sooner or later.
So don't for one minute think the open nature of the suburban network precludes GOA4.