The copyright holders (RealTree, Mossy Oak, etc.) only sell the right to other companies to print their patterns, they don't control the inks, processess, etc. You can look at the same pattern on four different makes of guns/garments and they can exhibit four different colors/shades.
Black guns may be cheaper, but they are no more effective than a camo gun. I've never seen a situation where the camo on a gun has hurt my chances at ducks, but I've been in situations where it definitely helped. I have seen situations where a black gun stood out like a black jellybean on a white cake.
You pays your money and you takes your choice.
If the gun you wanted was available in black and in camo for the same price
, which would you choose??
See, money is the only reason to buy black.