I would have to agree with Robert's line of thinking on this subject.  Everyone makes mistakes.  It is also important to evaluate the training that an employee is given.  Was it adequate, were there gaps.  Is the reason that this employee made the mistake a sign of vulnerability or weakness elsewhere, for other abstractors. 

Robert's point about the employee being more upset that he is can be very telling.  Do they get it?  Do they care?

It is also important to understand that the pace at which we are required to work these days simply means that we will make more mistakes.  Every error is not going to turn into a claim that requires someone to pay money.