North Korea's secrecy here is completely backfiring. It is counterproductive in two ways. Firstly, by refusing to even acknowledge the tragedy it invites speculation, such as the rumour that this was an assassination attempt. Secondly, a social system based on secrecy and fear is itself the breeding ground for disaster, as problems cannot be acknowledged or reported. So they go unnoticed, connections are not made, and so a number of small errors, such as signalling failures, or brake failures, combine to create a major disaster. This happens even in relatively open cultures, but the more the pressure for 'good news' the more this happens. Finally, in such a culture, what hope is there for learning from disaster? More likely, scapegoating will take place.
Finally, it is a sobering thought that in the recent history of North Korea, this tragedy hardly registers. The recent famine in North Korea cost the lives of over 1 million. The suggestion that this event will provide the impetus for change is likely to be wishful thinking.