Humans cannot detect emotion well

Nautilus reports:

The traditional foundation of emotional intelligence rests on two common-sense assumptions. The first is that it’s possible to detect the emotions of other people accurately. That is, the human face and body are said to broadcast happiness, sadness, anger, fear, and other emotions, and if you observe closely enough, you can read these emotions like words on a page. The second assumption is that emotions are automatically triggered by events in the world, and you can learn to control them through rationality. This idea is one of the most cherished beliefs in Western civilization. For example, in many legal systems, there’s a distinction between a crime of passion, where your emotions allegedly hijacked your good sense, and a premeditated crime that involved rational planning. In economics, nearly every popular model of investor behavior separates emotion and cognition.

These two core assumptions are strongly appealing and match our daily experiences. Nevertheless, neither one stands up to scientific scrutiny in the age of neuroscience. ...

Let’s begin with the assumption that you can detect emotion in another person accurately. On the surface, it seems reasonable enough. A glance at someone’s face and body language reveals what the person is feeling, right? Haven’t we been told that a smile tells one story whereas a scowl tells another? Raised arms and a puffed up chest supposedly display pride, while a drooping posture supposedly declares that someone is sad.

The big problem with this assumption is that in real life, faces and bodies don’t move in this cartoonish fashion. People who are happy sometimes smile and sometimes don’t. Sometimes they even cry when they’re happy (say, at a wedding) and smile when they’re sad (when missing a beloved aunt who passed away). Likewise, a scowling person might be angry or just thinking hard, or even have a case of indigestion. In fact, there isn’t a single emotion that has one specific, consistent expression.

Numerous scientific studies have confirmed these observations. When we place electrodes on people’s faces to record their muscle movements, we see that they move in different ways, not one consistent way, when their owners feel the same emotion. ...

Books and articles on emotional intelligence claim that your brain has an inner core that you inherited from reptiles, wrapped in a wild, emotional layer that you inherited from mammals, all enrobed in — and controlled by — a logical layer that is uniquely human. This three-layer view, called the triune brain, has been popular since the 1950s but has no basis in reality. Brains did not evolve in layers.

I think that this is correct. But why do most ppl think that they can read someone's emotions and feelings? I have met ppl who claim that they are very good at it, when they have no evidence of any ability at all.