In our neighborhood, a grandmother tripped over an English sheepdog, and it turned around and bit her in the neck and killed her. This legal problem went on for 3 years (the family fought the city which wanted to put the dog down).
Imagine the rest of the family could keep a dog that killed Grandma?
Well the compromise was struck... the dog was allowed to live, but without its fangs.

Then at work, a nurse friend of mine was mauled by her Akita, by accident.
It jumped up at her face ostensibly to play and it bit her lower jaw and ripped her lip off... which she was in shock and didn't realize. Her friends (they were all at a picnic) rushed her to the hospital, and she had to have extensive plastic surgery to repair it. Her brother took the dog to the vet, who said to put it down immediately since once they taste human blood, they will do it again. So the dog is history.

I also had a patient was was mauled in the face by a Rottie. It was not a pretty sight, and she was having recurrent infections from the bite which went from one ear across her whole lower jaw/face.

So it is not only pit bulls. I myself, am very nervous around large dogs.
I was bitten on the foot/leg, when I was 4 just sitting on my G-mothers porch.
A dog ran across from the other side of the street for no reason and attacked me. I'll never forget that...! I guess this is why we have cats?