There is a whole gamut of food allergies. Know a guy with a shellfish allergy who can still eat them and his throat gets scratchy and you can make a mild rash on his arm with shellfish. Another guy I know also has a shellfish allergy who went to the ER after his body went psycho because he ate something that was cooked in the same oil as some shellfish and throat closed up.

Because allergic reactions can range from "this is uncomfortable," to "Someone is going to die if we don't get an epipen right now!" It is best practice to err on the side of not killing someone, go figure.

While you do have to take personal responsibility when you have a life threatening condition, it isn't too tricky for most places to take appropriate precautions when they are forewarned.

People who take advantage of food allergies for attention or because they have an aversion to a specific ingredient water down an already nebulous public health concern with their bullshit.