My beef with the focus some schools have on peanut allergies is why single out that one allergen? Last time I checked people can and many do have life threatening allergies to all types of things. But you know what, no one ever bothered to ban dust, or cat hair, or peaches in schools. Heck, my highschool didn't even ban perfume and I can promise you it caused some big problems for at least one student who had multipul chemical sensitivities which are life threatening to her. So why keep the focus on just one allergy if the goal is to keep all kids safe.
1) much more likely to be anaphylactic, 2) much more likely to cause shock by contact with microscopic particles (dust, trace), 3) far, far more unpredictable than other allergies--a peanut allergy can transform from "mild" to "life-threatening" with no warning whatsoever, and 4) less likely to be outgrown.
Dd can go into shock if she ingests wheat, but she only has surface reactions due to contact. For many kids with peanut allergies, walking into a room where someone ate peanuts the day before can kill them. Dd's school goes to great lengths to keep her safe--we provide all of her food, she eats on her own placemat, next to a teacher, and all of the kids are required to wash their hands after they eat. But a kid eating a cracker in the room won't hurt her, as long as she stays away from it.
There simply aren't that many kids who have peanut-like allergies to other foods (and, again, I say this as a parent with a severely food-allergic child--over a dozen allergies, many of them extremely serious). If there are, then those situations can be dealt with on a case-by-case basis, finding ways to keep the kids safe.