It's a false economy, though, if the reduction in staffing costs is outweighed by a loss of revenue and/or increase in other costs (delays, operational incidents and so on). Even if guards are replaced by an equivalent number of ticket inspectors on a lower rate of pay, with a relatively very small cost saving, there's still the possibility of those other costs increasing to weigh it against.
I'd guess that the unfortunate driver being dragged out of the train on a spinal board had been involved in a collision with something, possibly in a relatively rural and inaccessible area. Who ensures the safety of the line, arranges for the emergency services to attend exactly the right location and looks after the passengers, if not the guard? There's every chance that the driver would no longer be with is, had that been the case.