I was thinking the same thing, as a child I never heard of people dying from these allergic reactions. Me, and all my friends, ate basically anything we were given at my house or their house and the idea of being careful of allergies was never brought up.
Even as an adult in the military in the 70’s and 80’s I cannot remember anyone having these kind of major reactions.
That’s because we were exposed to everything. A family friend was born allergic to milk. All her life, she has been exposed by her parents to small amounts of dairy so she could build up a tolerance.