People can be deathly allergic to peanuts, legume or not, and that tends to coincide with allergies to nuts.

There are regulations that say foods that may have nuts must be labelled that way because of that.

There's no reason for the regulations to add clauses like "unless the name of the product has 'nut' in it" because it's just simpler for everyone to be consistent and put the same label on everything, no matter how "obvious" people who won't have to go to the hospital if they eat the wrong thing think the name is.