My aunt was getting out of her car recently and a large dog came out of nowhere and jumped on her. She fell and broke her hip, still hasn't healed and its been 6 months.
I've walked around my neighborhood and one of the neighbors and two very large dogs that got out of a fenced yard ran up to me barking like police dogs while baring their full teeth. I am lucky the owner got out in time to control them. Owner smiled and said, "don't worry their bark is worse than their bite". That is not an acceptable response by dog owners who lost control of their dogs who are being aggressive towards a stranger.
So yeah, I think that's part of why some people have an aversion to dogs, based on some personal bad experience.