I don't live in the UK and here we do not have nearly as many of these incidents as you seem to, nor have I heard of anyone either dying after being attacked or being permanently mutilated.
Let's be clear about one thing: It is not the animal's fault, either when a dog attacks someone unprovoked or a horse throws his rider. Human error is the cause.
If you take on a rescue dog, you should surely expect that it may have been ill-treated prior to you getting it.
So either the new owners are not experienced enough at recogising danger signals, or the dogs' home is not getting to know the dog well enough and the potential owner before handing it over.
So one way forward is to get the government or local authorities to put stricter rules in place about re-homing animals.
Another is to make attendence at professionally run dog-training classes compulsory for all dog owners, whether or not they have had dogs before. These classes are to be paid by the putative dog owner, and anyone who won't or can't find the money or time, simply cannot have a dog.
Apart from teaching the dogs obedience and their new owners how to assure that the dog knows and obeys commands, and what to do if the dog does not comply, the owners can be assessed too.
Assessing the owners should judge both their fitness to have a dog, and whether this particular owner and the particular dog are a good match.
But unless you start lobbying nothing will change, will it?
Another point is, harsh as it may seem, that any fully adult animal, (dog, cat, horse, whatever) and many young ones that have been cruelly treated may never be entirely safe.
Whether we like the thought or not, it is better if the animal shelter and a competent vet or trainer is in doubt that the animal be put down than a risk of anyone, child or adult, being hurt is taken.