Catching the Bad Guys
Think you're a good liar? A polygraph might disagree. By monitoring a few physiological signs, these machines know if you're being deceptive, even if you don't have a "tell."
After you get a speeding ticket, you've probably mumbled (after the police officer left, of course) something about being stopped to satisfy a quota. Well, you're probably right. Lots of police departments have speeding ticket quotas.