Arsenic is an essential micronutrient with a toxicity profile similar to selenium (another essential micronutrient). Arsenic is sufficiently available in diets around the world that deficiency isn’t going to be a thing unless you go out of your way to aggressively remove it from the water supply.

Your attempt at an analogy was clumsy and nonsensical regardless. They aren’t serving poison at schools. Sugar would have been a better example.