Any Exposure Metering System, on pretty much any Camera, is going to Expose based on 18% reflectivity of Clear Sky Sunlight at High Noon. It doesn't matter if you are using Average Metering, Center Weighted Metering, or even the far more complex Matrix Metering that takes Colours, even Flesh Tones into consideration. The Camera, unless in full Manual Mode will still be picking an Exposure Value, and could be choosing Shutter Speed, f-Stop, ISO Setting to achieve that 18% on whatever it decides to meter on . Newer Cameras can also adjust the Contrast Levels, lightening the Shadows and darkening Overexposed areas. In a Nutshell, what your Eyes, see is rarely what the Camera records.
That said, many Cameras, offer various forms of Overrides to attain desired Results, but many people have Little or No Interest in Learning about the Basics of Photography.
