Many people might called that a useless regulation... but NO ONE who has a peanut allergy would say that.
You are right, it is very cheap to put that label on and solves NOTHING.
But like many conservatives and liberals, the answer to any problem is more laws and regulations.
You know there ARE other options besides passing laws. Can you think of them?
That did not happen.
Foods that do contain peanut products/derivatives say so on the label, the majority of foods are unaffected in the process.
For foods that DO contain peanut products/derivatives, the consumer is free to try to find a non-peanut alternative.
I don’t see that as being some sort of great burden/problem for manufacturers.
The same is true of phenylalanine. Foods containing it or it’s derivatives say so. And that is because there is a somewhat rare genetic disorder called PKU, and for people with PKU, even tiny amounts of phenylalanine will either kill them outright or make them spend the rest of their lives staring at the wall and drooling.
Is that a “useless” regulation?
Not if you have PKU. (phenylketylnuria)