Religious Freedom is the answer
Quenya is the language of the High Elves in Tolkien-lore. (I assume you had to read the Hobbit, maybe review it again, since this was a rather important point.) The trolls, goblins, and orcs mostly speak Black Speech, and the hobbits speak Westron.
It is safe when you have metal detector because it can also sensor thieves or shoplifter who wish to bring clothes outside the store. Metal detectors are useful to find hidden metal objects and can detect not just nearby but even metal objects buried underground.