Also, what makes this mistake common is the feedback you get.
When you make a false negative, you never find out that you passed on someone amazing.
When you make a false positive, it's professional embarrassment for the boss when he's forced to admit he made a mistake and fire them.
So the incentive for the boss is to minimize false positives, even at the expense of too many false negatives. The boss is looking out for his personal interests, and not what's best for the business.
When you make a false negative, you never find out that you passed on someone amazing.
When you make a false positive, it's professional embarrassment for the boss when he's forced to admit he made a mistake and fire them.
So the incentive for the boss is to minimize false positives, even at the expense of too many false negatives. The boss is looking out for his personal interests, and not what's best for the business.