Of course the driver knew he was there !
Tube train drivers sometimes do this (drag people along the platform) to teach them a lesson.
They get fed up when they can't get the doors closed which makes them late and therefore in trouble with their overseer. Drivers can be demoted for being persistently late (the whole line is backed up behind this train remember). Please don't beleive that drivers cannot see. That really would be very stupid and unworkable.
Anyway do not get caught in the doors or stop them from closing you could have a homicidal driver up front.