Jesus! I own a bull terrier and I will defend him and his soft as a brush temperament to the hilt. But I'd never leave him alone with a child, or adult who was nervous around him. Why the hell would I, he's a bloody dog. Can't be reasoned with.
And that wiki page about staffies says at the top not to be confused with which is just as well as they really are not the same dog. Similar history but many generations of wholly dissimilar breeding.
The American breeds had quite different jobs to do and were cross bred to get a dog that could manage a wide ranging, outdoor life. British staffies were not bred for wildlife management, protection.
But that doesn't mean they won't/don't harm a child.
And the 'lock their jaws' thing is also one of those hyperboles/myths. String jaws yes, locking no.
I only add the last points as I think it doesn't help to promote disinformation about dogs. It only hides the truth, that all dogs can do harm and kill. That leads to more incidents than are necessary, because Noodle the Poodle, etc, aren't dangerous dogs, for example.
But mainly it's down to owners. For how they treat the dog in general and how much or little they take care to remove the dog from situations where it can go horribly wrong.