I have found most big bucks on public ground in our area don't expose themselves to the road hunters long enough, if at all, to get shot. Not to say that the occasional undeserving spotlighter or coffee sipping dodge hunter, doesn't shoot an occassional monster buck that should have gone to someone more deserving. Most experienced hunters in our area use the way the game avoids the roads to their advantage. Some of the best set up spots when the bucks are chasing does are just over the backside of ridges from roads, you can still here cars drive by, but the deer must know they can't be seen and use these travel corridors.
I think the case could be different in non forest ground such as in farming areas where the deer come to feed in open fields in the evenings and mornings, since they are not afforded the cover from drive byes.
I think there is more to not road hunting than just safety and ethics, it simply isn't as effective for producing trophy game as getting out into the bush. Any one who spends all their hunting time in a vehicle is robbing themselves of the better opportunities of being even a few hundred yards away from the road, and missing out on the enjoyment that comes from being engrossed in nature.