My understanding was that the drivers were originally added partly in response to the "Fremont Flyer" incident, where a test train under autonomous control drove itself off the end of the track: https://www.flickr.com/photos/walkingsf/8143196966
Even today, the automation on BART is far from perfect, and the drivers are more involved than most people realize.
The trains still like to over-shoot the end of stations, requiring the driver to quickly initiate a manual stop. (The stop signal is RF based, and apparently sometimes the train misses it.)
On top of that, they often need to drop down to manual control for certain sections of track, for various reasons.
Even today, the automation on BART is far from perfect, and the drivers are more involved than most people realize.
The trains still like to over-shoot the end of stations, requiring the driver to quickly initiate a manual stop. (The stop signal is RF based, and apparently sometimes the train misses it.)
On top of that, they often need to drop down to manual control for certain sections of track, for various reasons.