Small people shouldn't be left alone around any dog. Fact: People, especially small people, are unpredictable.
You are wrong. No dog just "snaps". And Pitbull temperament is quite stable.
Your dog sense detector is broken if you believe people who say they had no indication their dog would bite. Knowing they might would require something called paying attention though, and doing something about it.
Btw, Good fences make good neighbors. No need for killing "just because".
How do you know "99% of attacks don't make the papers anyway"? I'll be Nice and just say you're clueless.