You assure your bus driver doesn't have a habit of popping pills by making them go through rigorous certification, give them decent wages, and punishing them ha

You assure your bus driver doesn't have a habit of popping pills by making them go through rigorous certification, give them decent wages, and punishing them harshly when they do pop pills. You may object it's not perfect, but nothing is, and it does work. In fact, it works exactly the same way you can assure that your brake pad won't suddenly give way in front of a bus coming from your left.