It occurred to me while reading this thread that possibly you all are discussing two different things. There's the people discussing the contrast within an image and if you can see it or not, example "driving at night"
This is the question of "can you see"
The answer is obviously yes to this.
But there is another question, if you took the image that you have in your head of seeing at night time, and reduced it's contrast in the scene to 300:1 or 100:1 or whatever you want to agree on, would it actually look different to you?
That's a much more difficult question to answer, and at least to me does not have a clearly obvious answer to it.
So while you can "see" perhaps 1,000,000:1 images just fine, do these 1,000,000:1 images actually look any different to you than the same image that has had it's contrast reduced by some method to 300:1 or some other low number.
Edit: Also I don't believe the putting your hand in the shadow of ANSI test is quite the right test for this, since that changes the picture and your mind may be equalizing the contrast in some way to actually "see" this difference, perhaps the white was decreased visually to you to accomplish this?
Also the visual tricks of how putting light colors by dark colors changing the percieved lightness etc supports that this can be happening.