Neither do the Military demo teams. They plan their flying so that it does not pass over the crowds. It is a FAA requirement for an aerial demo. Aerobatics are not dangerous unless you are really inexperienced or try them too close to the ground or both. Military pilots are all taught Aerobatics as part of their basic flight training.
Better said near crowds, not over. However, when pre-positioning for the low altitude high speed run, sometimes zip over people and boy-howdy, does that wake everyone up.