What is up with this and "DUI" drivers?

I went on a "Ride along" program the Sheriff has here in my county, nothing happened till around 2 AM, we got behind a car on a back road (2 lane paved county road) that was all over the road, ditch, mail box, back on road. Deputy said "Watch how we handle drunk drivers around here". he finally got it pulled over, radioed in what was going on and went up to the drivers side window, talked a few minutes and the car drove off, I asked what happened, he said "the driver wasn't drunk, just tired and only lived 1 mile down the road". I would think the driver should get the same treatment as a DUI driver, bad driving is the same, drunk or sober, like I would get killed more dead by a "DUI" driver than this woman driving "Tired"? I would think ALL bad drivers should be treated the same, no matter what caused you to crash.