Here's a fun experiment. Using auto-exposure mode with flash turned off in your camera, fill the frame with a solid pure black image (like a black piece of paper) and take a jpg picture. Then, fill the frame with a solid pure white image (like a white piece of paper) and take a jpg picture. Now, compare the two pictures and tell us if one is pure black and the other pure white -- just like what you saw and SOOC.
That's a dumb experiment and unrelated to taking photos SOOC. SOOC doesn't require ignorance of camera meter functioning.