Whyisitsodifficult
We do eat out despite having a child with nut allergies. Here's the difference between eating out and her being exposed to kids eating nuts in school. I'll type it slowly so it's easier for you to understand but really I would have thought you could work this out for yourself.
When she's with us in a restaurant, we can watch her closely so that if someone else eats nuts we can prevent them from touching her.
Also because we are with her we are alert to any signs of allergic reaction, which means we can treat her immediately.
On the other hand, in school she has been in situations where an unsupervised child has eaten peanut butter then either touched her or (my personal favourite) waved the peanut butter sandwich at her face to wind her up.
When she had a reaction at school it took a while for anyone to notice, because they had a lot of children being supervised by a small number of supervisors.
I can't explain why so many more children now have peanut allergies but as it is clearly true perhaps instead of whining about it we could try to make their lives safer instead of whining about how unfair it is to have a food group removed from your lives in some limited situations?