They said if the driver passes out the horse will go through intersections. It's not like the horses know the traffic rules on when to yield, stop and go. Even, if the driver doesn't pass out their reflexes and perception are still bad and they might think they can get beat a car or train through an intersection. I don't see how it's any different from being intoxicated behind the wheel of a car.
You're taking this WAY too seriously. Besides, my horse quit drinking a long time ago (but I think he still smokes a little weed with the dog).