Most of the time, in my own experience, when I am close to falling asleep while driving, I would have never been able to realize how tired I was before leaving on the trip. Even if you feel wide awake before you leave your destination, a late night drive on the highway can induce sleep, with the hum of the highway and the flying by of the lines on the road.

You're basically suggesting that people decide to not get in their cars if they even slightly think they might be too tired to drive. You know as well as I do that there's no way to measure this (unlike drinking, where if you consumed any alcohol in the last several hours you shouldn't get behind the wheel.) So, it's a bit of a pipe dream to think drivers are actually in the position to make a judgement call about their own risk of falling asleep at the wheel before leaving.

Regardless, my point was that these safety systems are meant to protect responsible drivers from irresponsible ones. I'm skeptical that the presence of safety systems could somehow convert a responsible driver to an irresponsible one.