An open door is a safety concern, not an emergency. As long as everyone stays away from the open door, they are fine to allow the train to navigate to the next station. Common sense is important and should tell you not to do anything stupid. The people in the pictures below don't seem to have a problem with open doors.
That does not excuse the system's failure to issue an open door alert. But, if it did alert the driver, the best solution would be for the driver to instruct everyone to stay seated until they arrive at the station.
I once rode a train in Philadelphia that was on fire. The breaks locked up on the last car and friction caused them to catch fire. The conductors moved everyone to the front cars and every stop they put out the fire and checked to make sure it wasn't spreading. This was done until we were able to get to a switch line. That act kept the entire system from grinding to a halt due to a stopped car on a one track section.
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