I think that’s largely due to the nature of their job. I’ve had the experience in the past, I lied to my therapist about a very sensitive issue. I told I was perfect with it, I hadn’t stepped out of the building before I got a text from Mr. Warren my therapist, “Hi Fraser, I’d really like to walk this journey with you, but we won’t make headway if you keep hiding the truths. Don’t be late to your next appointment as we would be starting all over”. Not only did he know that I lied about everything I had told him in the room earlier, he also didn’t try to tell me I was lying. He patiently listened to me and watched me closely, almost as if he could see through me. He knows I would’ve felt embarrassed if he called my attention to the fact that I was lying, rather he chose to let me leave then sent me a text. I believe it isn’t simply their thing, they’ve grown to master other people even more than they know themselves.