DH takes a peanut butter and jelly sandwich on cross country flights all the time. He travels at least once a month to CA. He's never had that request made, but he makes that particular sandwich because it doesn't require refrigeration and fills him up. While no one wants to endanger anyone, it's hard to expect 100+ people to be happy that because of one individual they have to not have a food they may have brought with them. As others have said, if I had a child that was that allergic, I wouldn't be dependent on those on the plane to be as careful as I would. BTW, there are packaged foods that you think don't have peanuts in them, but may have been made in a plant that makes other items with it and peanut dust does travel. In that case, completely innocent and unaware. Reasonable accomodation is what is supposed to happen. Now, I'm not sure that asking those on the flight to be 100% responsible is necessarily reasonable.