4.1 – 1
With the camera in Aperture Priority.
You don’t even need to look at the histograms to see that in an auto mode, the camera has averaged the brightness of each image, so that regardless of whether the subject was black, white or grey, they all look pretty much the same.
4.1 – 2
Now with the camera set on manual.
With the camera set to manual, and exposure adjusted via shutter speed, aperture or ISO settings, the subjects can be made to look the shade you would expect them to be, which is reflected in the histograms.