And we haven't eradicated the common cold. So what? People are not germs, and detecting psychopaths is tricky. False positives means you kill innocents. False negatives means you create survivors who now have selection pressure to avoid detection.

But this is all pretty obvious. So what are you really trying to say? Are you signaling that you don't like psychopaths, or are you literally proposing setting up death camps? If we are fantasizing, why not be nicer and posit an empathy chip?