Why did they have a crosshair in the other versions? Where there sections moving the crosshair was involved?
The answer to that question is that the original arcade game was a conversion kit for Cobra Command another LD game with a crosshair and they simply used the same framework to design Road Blaster, change out the flight stick for a steering wheel, a new ROM with the engine, and new video.
I've not played an actual arcade machine of it (apparently Data East only managed to sell around dozen conversion kits for it in the US as the arcade industry was in a major slump in 1985, LaserDisc games had high failure rates and the arcade operator had to already have a working dedicated Cobra Command LD cabinet to convert from) but from what I recall of the 32-bit ports it's mostly used to see how far the wheel is turned in any one direction.