Exactly. From what i’ve encountered, polygraph testing is better for intimidation purposes than detecting lies. The polygraph machine can not read your mind. It measures heart rate, pulse, sweat. The interrogator “interprets” the data and decides whether one is deceptive or not. So it’s very fallible.
What is really frightening is how when a guy fails a polygraph it is assumed by probation that they actually committed whatever violation they were flagged on. If they say they didn’t do it they are punished for not confessing/incriminating themselves. If they admit something it seems they are punished just about the same.
Rock and a hard place.