Living with allergies such as a severe peanut allergy is all about mitigating risk
In most open areas you can be cautious about what you touch and who you stand near to. In enclosed spaces such as airplanes, the risk is substantial and mitigating it requires as close to an absence of peanuts as possible
And peanuts are special in how easily they trigger severe reactions. Of all my son’s allergies, peanuts are the one that scare us