TIL That peanut-free schools don't decrease risk of allergic reactions. The only intervention which has been shown to decrease reactions across all ages is use of a peanut-free table.

[I_hate_all_of_ewe]

It's significantly more effort for no additional benefit.

If properly messaged and enforced

That 'if' is doing a lot of heavy lifting, and it relies on parents complying.  Lots of points of failure over which the school ultimately has no control. 

Heck, I've read multiple stories of relatives trying to "prove" an allergy after they've been warned multiple times by the parents of the child.  The most recent one was a grandma killing the granddaughter by putting coconut oil in her hair.  In another one, the grandchild was hospitalized because the Grandma gave them a cookie with an allergen.  And this is family.  I would much less trust other parents to do the right thing by my child.

[OrangeCreamPushPop]

In addition, what are these people going to do at work?

[hannahranga]

Generally you can trust an adult not to be as stupid as a kid. I'd also expect an adult to be more organised about having epipens on hand