In lieu of Invented, the proper term is "mass psychogenic illness".
No one was lactose intolerant back when we were all getting milk in school. 1950's
I was born in 1940 and have had severe asthma and allergies since childhood. Back in the 40’s 50’s and 60’s I can assure you, no one was keeping score. But there were people who could not tolerate milk, etc, etc.
No problem with me and peanuts, I love a good PB&J and a glass of milk!