Why shouldn't you call 911 for an accident? You aren't trained to triage these sorts of situations, the people answering the 911 call are. If you call, explain

Why shouldn't you call 911 for an accident? You aren't trained to triage these sorts of situations, the people answering the 911 call are. If you call, explain the situation, and they respond by sending an ambulance, then surly that indicates that an ambulance was necessary.