I have to wonder if some of these parents just assume that the possiblility of airbourne peanut dust, or the mere smell of it on someone will kill their child, or have they had real past experience with their child having a "life threatening" reaction in those circumstances? Just curious. Is it based on fact, or fear?
For me, it is a combination of fact and fear.
There was a study done in the 1990s on roughly 60+ patients that had a reaction to peanuts while in flight. The study determined what was the cause of the reaction. The majority of the causes were due to consumption of a food product that had peanuts in it, the second cause was in children picking up/touching loose peanuts that were on the plane. The final group of reactors (the smallest) group were due to airborne inhalation and skin contact with the product that was on the plane somewhere on the plane.
Noteworthy, is that none of the 60+ people died but one portion of them had to received medical treatment in flight, while the other had to receive more treatment post-flight.
Now, like you, we are pretty loose with our peanut restrictions at home. We have PB in the house, my husband is the one who eats it, I don't care much for it but I do love a Reese's now and again and will eat them. My son lunches with his classmates at a table where PB&J is served and does everything else a normal child does.
What we cannot "replicate" at home just to test it out is a confined space with poor ventilation, and MANY people eating loose peanuts. I honestly don't know how he'll react so I have to look at things like the study information I provided above and make some choices based on that. I also have to take into account that, on his allergy tests, he exhibits one of the more severe reactions. This test is only a predictor of how he might react given the right (or wrong) circumstances.
He did react one time on a plane by his legs breaking out in rashes after he sat on the seat of the plane. But he has eczema anyway and, quite honestly, anything could have done it but, really, that type of reaction is not a common occurence with him when he sits on strange seats so I concluded that some allergen made contact with his skin. He wears pants on the plane now.
I also wanted to add that 14 years ago, when we first learned of his allergy and for many years after that, we did NOT fly with him. As parents of a young child, understandably, we were not as laid back as we are now, plus we had doctors being VERY serious about it. And at that time, the airlines were not doing anything about flights that I am aware of. My son's first trip to Disney was when he was almost 7. We never felt we could go before that (with him) because we didn't feel that he was going to be safe on a flight. Once the airlines started making policy on this issue (not at OUR request), we felt like "Hey, maybe this is something we can try." And of course, Disney is wonderful with allergies. That's pretty much why we don't go anywhere else.