I just had crunchy peanut butter on toast for breakfast, I eat that quite often. I also take a PB and wholegrain sandwich with me on trips, it could easily happen that I ate my sandwich, then boarded the plane, and sat right next to someone with deadly allergies. I certainly do not wash my hands every time I eat at the airport.

I 100% feel for the family, but if the allergy is that sensitive I would be always concerned about public transit, and carrying way more than two epipens, their effects are pretty short lived in terms of a flight.

All the announcements on the planet can not fix the fact that many folk have allergens on the hands and faces, let alone the fact that planes are far from well cleaned.