That's not true though. You not only can't necessarily prevent them, you may be the cause of them. On average a child a week dies at the hands of it own parents. Some 500,000 children are abused every year, most commonly by parents, carers or family members. Those are also all "preventable", but the people who should be preventing them are often the perpetrators or complicit. Over 800 children aged 1 - 9 years die from accidents every year. Those are also mostly preventable. Deaths resulting from dog attacks are in single figures.
That is not to say that dogs can't be dangerous. Lots of things can be dangerous. Lots of things are more dangerous, and parents are amongst them! We don't suggest banning all adults from being parents and seizing children at birth for their own protection. As a country we do bugger all about teaching parenting. And when a child is killed by their parents, everyone is quick to point the finger of blame at the social workers, schools, and other people who didn't kill them as if that is all their fault.
So ok, dog attacks are, in many cases, something that you can prevent, just as much as you can prevent many of these other deaths. And people should be more responsible. But guess what? People aren't. Punishing those who are responsible, those who will train their dog, observe the rules, have insurance, use the vets etc is not the answer. Those who aren't responsible will never adhere to the rules - because they don't adhere to any of the rules on anything. If they teach their dogs aggression, or abuse their dogs, then you can almost guarantee that the same applies to their children.
And as for those who advocate banning all dogs, I'll just let my service dog know that he's no longer required because he might be dangerous, then give up work and go on benefits since I won't be able to function without him.
All dogs can bite. Most dogs don't.