I get tired of hearing that, too.
My son got attacked by a dog, a german shepard/chow type mix.
Exact words out of the owner’s mouth “He’s never done that before.” The dog knew my son, and they’d played before, but it just snapped I guess. The dog went straight for his neck, and he has the scars to prove it.
That said, the dog did let go, and I believe a pit bull would have ripped my son’s throat out.
This is the exact reason my husband and I had a separate pen built in our fenced-in backyard for our German Sheppard to go into whenever we have company over. Our dog has never bitten anyone, but we’re not going to take a chance on the first time.