You are committing a common fallacy - when evaluating risk, you are considering only one of the alternatives and forgetting the risk of the other. Yes, nobody wants to be operated on by a yahoo. But mortality is not a good measure of yahoo-ness, because in some cases not operating carries larger risk of death than operating. And if a surgeon decides to operate in this case, the decision is right even if resulting risk is high - because the alternative is even higher risk. Considering only mortality rate of operations ignores this. It is a variation of survivorship bias, only on the opposite side.