The main property of fingerprints just like faces and other biometrics are supposed to be not detachable from the thing (person) they represent. Therefore the a

The main property of fingerprints just like faces and other biometrics are supposed to be not detachable from the thing (person) they represent. Therefore the authentication processes based on them should somehow guarantee the presence of the person itself. Usernames on the other hand are separate entities and therefore it is necessary to provide a secret for authentication. A key from a house can be also passed to other persons and hence that person without any protection, and hence that person should additionally authenticate itself as a true owner.