Ones who hire coaches prone to such actions. Most of the states that have enacted legislation to protect sports officials have increased the penalties imposed when a sports official is assaulted. Part of this helps to increase the likelyhood that an official will press charges and help other officials by bringing these problems to light. Many times attacks go unreported because the offender gets off ridiculously light and it is not worth the time and effort that you must put forth to see it through. Yea, I've had things thrown at me by a coach, been grabbed while leaving the court by a coach, etc.
Gutless administrators is the problem.
Ones who hire coaches prone to such actions.