She was carrying a very expensive violin. She got off the train and the doors closed between her and the violin, with the strap around her shoulder. Because the strap was thin, it didn't activate the door's obstruction detector.
Because the violin was so expensive, she didn't want to lose it, so instead of crawling out of the strap, she stood there and waited for the conductor to notice her. One of his jobs was to verify visually that there were no problems in the station before the train started moving -- but he didn't do that. She was dragged under the train and the wheels sliced off her legs.
Point being, those people are likely serving an important safety function. The conductor didn't do his job on the Chicago train and so a woman lost her legs. But a system with no human conductor would be an unsafe system by design.
Perhaps, yes. But in this example, with no human conductor, the woman would have just sacrificed her violin instead of relying on the unreliable human conductor.
Hell, my garage door 20 years ago did it.
One guy presses a large "Go" button to leave the station, which is automatically stopped at, and there's also an emergency stop button.
The other guy has an "open / close door" control.