Trouble is, drunkenness is on top of all those other factors, not an alternative. And drunkenness has an effect of causing people to unrealistically underestimate the risks associated with many of the other factors, an dthus be less cautious than they otherwise would be. IOW, yes a 75 year old driver is statistically equivalent to the mildly intoxicated middle aged driver. But the 75 year old whose had a drink or two, is not only more impaired than before, but also less able to perceive the degree of risk associated with either form of impairment. An unintoxicated 75 year old is usually well aware that his/reflexes aren't what they used to be, and that he/she needs to be extra careful while driving. A mildly intoxicated 75 year old will often be oblivious to those facts.
I can agree with that. I'd bet a majority, perhaps a vast majority, of all alchol related deaths don't happen because the driver had impaired reflexes, but because they were reckless. There is no breathilizer for 'gumption'. :)
But, I'm not sure how to settle the paradox of this individual variation in order to fairly define a DUI, as laws cannot really be written that way (unless an objective reflex test or something was developed)... now that would be interesting... :)
I'm not one to get hot and bothered over our current DUI laws, sure some might be a bit unfair to certain individuals, and too lienent to others, but I'm not sure how you change the system to make it 'fair' and there are plenty of more important things to put one's time and energy into fighting...