Banning breeds doesn't work, we've 20+ years of proof of that. You have to ban crosses of those breeds and that leads to dogs being typed by appearance. The more breeds you ban, the harder those who wish to own intimidating and dangerous dogs will work to hide them, own them, and of course, produce NEW types of dangerous and intimidating dog (see bully kuttas, bull terrs, alaunts, etc).
Licencing costs too much to run, and would be avoided by the people who cause the issue.
The answers are, education - starting in primary school, covering animal behaviour and how their needs are important, space must be respected etc - that can be worked into a variety of subjects through primary and secondary, and in secondary, covering things like 'don't go and buy a dog to make yourself feel safe when you leave home' in some areas.
The issue is people - we do not punish PEOPLE when things like this happen. The kid suffers, the dog suffers, the adults who were responsible are deemed in almost all cases as 'having suffered enough'.
I can quote you multiple cases where children died because adults CHOSE to place them in the care of people who had child aggressive dogs; large, fearful dogs; dogs trained to be aggressive to humans; dogs with no known background; dogs recently moved into the home.
All of those things are risk factors, add in other stressors like strangers in the home, fireworks going off for weeks on end, heat waves in summer - it is in some cases a recipe for disaster.
Many many dog owners believe they either know all they need to know about dog behaviour OR are wholly unaware there is anything they need to know. You only need to read Mumsnet to see people discussing dominance and alpha dogs and pack leaders to see how many people are totally clueless.
So we need to find a way to reach those people, and that is not easy.
We also need a massive overhaul of HOW we deal with such incidents - in this case I believe the dog was shot on site, not as a way to get the dog off the child (that just wouldn't happen) but because there wasn't anyone to handle the dog with the skills required.
What really should be done is dogs in such situations be seized by appropriately skilled handlers and taken to assessment centres to be evaluated by professionals.
This is NOT so that the 'dog can be saved' - this is so that the dog can be treated like the evidence in a criminal offence that it actually is at this point.
From such assessments it is possible to tell.. a/ that it was indeed a dog that did it, b/ was the dog trained to do it, or was it provoked or not, c/ was this a fluke incident or actually could this event have been predicted and avoided...
There have been cases where dogs have been used to cover up human crime.
For example, human bite marks passed off as dog bites - the dog in question was seized, his bite imprint taken, compared to the wounds, proven not to be the dog.
Dog bite marks used to cover other injuries - a childs body was found with bite marks, however comparison of the dog in question, the bite marks and the dogs behaviour showed that the dog couldn't be provoked into biting, unless in play.. and the childs body had injuries under the bite marks. In fact the child had died of injuries inflicted by adult humans and then they had enticed the dog to rag on the dead body to hide this.
Some of these things can be told from necropsy on the dog but many cannot and require a live dog.
At present not only do we not have the skilled officers on scene to handle such dogs, we do not have enough professionals to assess them (we have several, but not enough to cover the whole country), and most importantly we do not have appropriate facilities to house and assess such dogs humanely, in a way that would not alter their behaviour significantly (holding kennels for seized dogs under the DDA are awful and will turn the nicest dog dodgy in many cases).
As long as we keep punishing the dog, and not the people responsible for the dog, as long as we avoid educating people, and continue to euthanise and incinerate evidence without proper evaluation of it - this type of tragic incident will continue to happen.