Man in Australia Tasered to Death By Police

These incidents seem to be piling up over the last year or so.  The taser has long been the police’s friend, touted as a safe way to control subjects and an effective way to avoid using deadly force.  However, it seems that tasering in some instances can be deadly.  Is this a lapse in good judgement by officers in these individual incidents, or is the taser more dangerous than they want us to think?