The statistics for injury and fatalities by dog bite do not look good for Pitt Bull breeds.
All breeds are unpredictable and capable of turning. I never let my guard down when my sweet tempered Jack Russell is around a child.
I am sure there are responsible PB owners but these dogs have physical characteristics that make them more dangerous. They do require extra attention and not all PB owners are capable or responsible. Some are down right criminal in how they care for these animals.
If you were riding or running down the country roads that I do and you saw a snarling square head dog bearing down on you, you would not pause to consider how responsible its owner might be. You would fear for your well being and assume that this animal intends to do you harm.
This is my reality all too often.