There is no more higher probability of driver impairment causing a 1 car crash than a 2 car crash, and even if it is higher, I don’t believe it would be so significantly higher as to make checking for impairment protocol in one and not the other.
You’re making this up. Give us proof.
logically you may be right that there is no more higher probability of driver impairment causing a 1 car crash than a 2 car crash, but there may be a higher incidence of one car crashes caused by driver impairment. Either way I don’t think you change the first responding protocol but I wouldn’t really know, I’m no wikipedia buki.