George writes:

Why, if you're correct, do they have train operators present to make
announcements, close doors, and operate the train in case of
unforeseen difficulties
???

A human being is always handy for unexpected situations, and since BART was
one of the first fully automated systems, it had a lot of problems initially.
There may be union requirements for people, too.

The fact that a human operator is aboard a train doesn't mean that the train
can't operate itself in normal service, just as the presence of pilots aboard
an airliner doesn't mean that the airliner cannot fly itself most of the time.

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