There is also a large percentage of motorists under the influence of heavy prescription drug regimens. Some that would put me in a coma. In over 45 years of driving, I can’t recall more distracted and disengaged persons behind the wheel. Electronics and other digital devices aren’t helping much either.
Yes, Ambien having been one of them prominently in the news lately, but any number of psychotropics could affect alertness.
Hopefully, it seems they are starting to test and classify these cases better, in more detail, so that we may have a clearer picture in a few years, rather than automatic and generic DUI/DWI. Though many might have multiple drugs in their system, some may be shown to be prevalent or primary.