Most of human behaviour is driven by the non-conscious parts of the brain. This is why criminal profiling is useful, and how lie detectors work. If we were always 100% conscious of our decisions and actions, and had full control over them, then such behavioural predictive measures would be useless.
I agree with your point, but what makes you think that lie detectors work? Over here they're _forbidden_, precisely because they _don't_ work. They measure how excited/agitated you are, not whether you're lying.