You're all are crazy, people No matter the technology, lower voltage usage always going to be on the side of displaying darker colors.
Displaying lighter pixels (bright colors), is more draining on the battery than to display darker pixels (dark colors). It's like if you light two fires and will want to make the second one brighter than the other one, you'll have to feed it more wood. No other way around it.
You don't understand how an LCD display works. The pixels on an LCD display do not light up, they just let light through. On a phone LCD display there's a single backlight unit behind the LCD that provides all the light. This is the part of the display that uses almost all of the power.
There's one backlight for all of the pixels.
If all the pixels are white, the backlight is on and is using power.
If half the pixels are black and half are white, the backlight is on and using power. The LCD layer is blocking out that light for half the pixels, but the light is still on.
If all the pixels are black, the backlight is on and using power. The LCD layer is blocking out all of that light.
Just because there is less light going to your eyes doesn't mean that that light isn't being generated. It's just being blocked out by the LCD layer to make the 'dark' pixels.
There's no way for the backlight to use a reduced amount of power just because some of the light is being blocked out by the LCD layer. The backlight is either on or off for the whole display and uses power based on the brightness setting.
Edit: To use your analogy, think of an LCD display as a big fire with a stencil (cutout shape) placed on top of it. You look down at the stencil and you see light through the holes and black where the stencil is. No matter what stencil you use, even if it has no holes at all and is sold black, the fire is still going underneath and using fuel.