You'd be surprised how many people...the kind that rarely drive after drinking...nearly miss hitting something and panic. They're scared. The only thing they can think of doing in their drunken state is to call the cops, thinking that the cops will appreciate their honesty and/or desire to to get off the road and give them a ride home.
I should have said "made the best out of a bad situation." Correct, the right thing would be not to have driven drunk in the first place. But given that she did...