Well . . . actually deer can see color. Dogs can see color too. It's just different for them. Deer have deeply attenuated red vision that makes hunter orange look like the color of maple leaves getting ready to fall-- a rough approximation.
This brings up an interesting point. Why is camo such a good, necessary thing in the military and not with deer hunting? The answer is kind of complicated.
First off, human brains just aren't tuned like prey species. A deer's eyes and minds are much better able to pick up movement. Our eyes are better able to pick up subtle color differentiation.
Second, we understand our world in a completely different way. We can anticipate danger and dangerous situations a lot better. We can reason things out. An animal sees a lush growth of alfalfa as a bonanza in the middle of the forest. We however, can see it as a food plot and a potential ambush site. We also understand that a hunting blind might have something inside of it.
Third, we have a better-developed theory of mind (what goes on in the other guy's head). Deer stick their heads behind a tree and they think they're hidden, even though their butt's hanging out. We can anticipate what the other guy's thinking.
Humans also have a concept of mortality far better developed than a deer. I've watched a lot of deer. Believe me when I say that their concept of life and death is not like ours.
Lastly remember that modern military camo is there to not only fool human vision, but that of electronically enhanced vision (night vision, etc.) It always blows my mind when I see pixellated camo meant for hunting animals-- like the deer and turkey are somehow going to get night-vision scopes!
