Remember, James Bond or Jason Bourne using somebody else’s fake fingerprints to scan through the machine and gain access to whatever they seek? Well, in reality, such fakes could be easily identified by the machine. Getting access to a print or dismembered finger doesn’t let you gain entry as biometric machines are too smart for that.
Plus, these agents do have a busy day in the field, with the possibility that their hands might be dirty or cut, such flaws, the machine could easily detect. If the authentication is wrong, the machine would ask for all finger-scanning, enough time for the crooks to catch our hero/heroine.