Common sense from the dark ages

Now it seems like the discussion is which causes the most accidents, i-pod, blackberry, hand held or hands free cell phones. Do we need a law for texting on this device or that one?
Well, back in the day, when I was learning how to drive I seem to remember a low that said, not devoting full time and attention to driving was against the law.
Where did that law go? Wouldn't it cover changing radio stations, texting, watching videos,putting on makeup, correcting children, looking at a map, or anything that would take your attention off the road?
If you wanted to do any of the above you were to pull off the road. If you did it while you were driving and caused an accident YOU WERE NOT DEVOTING FULL TIME AND ATTENTION TO DRIVING, PERIOD.
One law, problem solved.
Of course I can see how this would upset people who make it their life work to write and rewrite all the laws, not to mention the lawyers.