It's prety easy when doing the post-mortem of any accident to conclude that it wouldn't have happened "if the victim had been paying attention" - chalk it up to pilot error (and infer that "I am better then that and it won't happen to me"). But accidents do happen and human nature is what it is.
it is well know old eric. In the text of McCammon 2002, the author explain that: "The familiarity heuristic is the tendency to believe that our behavior is correct to the extent that we will have done it before" (McCammon, 2002). Probabaly that he did the rapp many time and he tought that he was correct because he rapted many time and made a mistake.
Contrary at Dman, who accused the person to be careless, I suggest that people understand what McCammon explain and understand what they said.
It happen to every of us. We saw the hold on the right, we concentrate to place the right hand under the hold and grab the hold with the left...we do the move and we use the right hand instead of the left. some time, the brain do the contrary of what we want to do consciently.
Those kind of accident is not a lack of knowledge or that the person don't pay attention. It is a way that our brain work and we have to understand it to be safer.