A number of commercial vehicles have black hood treatments that don't have roof-mounted lights. Kansas Turnpike and Chicago-area highway department vehicles, for example.
The objective of low-glare treatments is preventing oncoming light from being reflected up into the driver's eyes, as I understand it. An optically-smooth surface will reflect a high portion of the incoming light specularly -- glancing off the surface at the same angle as it was incoming. The combination of black color (for high absorption) and low gloss (to give diffuse reflectance) will reduce glare from incoming light.
With respect to roof lights specifically, one could almost imagine that a black, low-gloss hood would be WORSE for roof-mounted lights. The last thing one wants is to have light reflected back toward the driver. A shiny smooth hood will send the roof light off down the road. Now, where roof lights lead to reflectance back toward the driver from objects down the road, a black hood may help -- the high light position is exactly the wrong angle for the specular reflection mentioned above, and could be right into the driver's eyes.
Don