>WHY?
The professional being paid are responsible to assist. If John goes in to help and underestimates a situation and now also becomes someone requiring help. John has only the goodness in his heart, not the required skill in his brain to render effective situation.
Now for the other side.
The professionals don't want any John's who have no budget, training or organization to show up and demon straight to the world how utterly limp the government is when shit hit the fan and get real.