From the dogs perspective, no it wouldnt have been an accident, it would have been a choice. From the owners perspective, I can't imagine any situation in which a human pet owner would actively encourage their dog to attack to kill a child. So putting stricter regulations on dog owners would have no bearing.
As pointed out by PP - dog attacks that end in death are usually triggered by something, no dog attacks for the fun of it. In this circumstance i believe another poster said it had come to the family a week prior - if this had been down a shelter route - the home would have been carefully vetted and not placed in a home with visiting children should it not be deemed appropriate around children. Infact most shelters don't allow dogs to be placed in homes with children under 10 as a standard rule. If it has come from a random friend/stranger - then yes completely owners responsibility to inform the new owners of any concerns - if there is any. If there has never been signs of aggression before, how can you give a warning. And that is not uncommon.
The whole point of my arguement, is that you are effectively trying to control the uncontrollable. It is not certain which dogs will be dangerous and which won't, so the only means of control would be a blanket ban - which will never happen, but even if it did - where would it end? Horses throw riders off and kill them, but that's deemed acceptable and not such cull of horses is being called for.
Dogs are ANIMALS, certain have been bred (rightly or wrongly) to bring out the best of their particular strengths and just like anything in this world, the bad people have turned their hand to breeding dogs to perform to their strenghts (such as fighting). That doesn't mean every dog should be tarred with the same brush, that every dog should be on a lead at every opportunity.
Of course it is horrific that anyone would die in such a horrid nature, but there is little to no-way to effectively police or manage human actions (else murder, rape, terrorism also wouldnt exist) to breed/manage safe dogs. And without a blanet ban of dogs - this will continue. All we can do is look out for ourselves and our familys.