why it cannot detect some profile face?

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Hi all I was trying to detect profile face. I found it's possible to detect it using haarcascade_profileface.xml. But I confirmed it could only detect a left-side face. How can It detect the other side face?

Here is a example. The size of image is 960x703.

face_cascade = cv2.CascadeClassifier('haarcascade_profileface.xml')

faces = face_cascade.detectMultiScale(gray, 1.3, 5)