I remember seeing a lot of horses tied up outside a bar in Scottsdale back in the late 1950s and early 1960s on Friday nights. A lot of the cowboys from ranches in the area would ride in on payday, drink up their paychecks, get on their horses and let the horses take them home. The horses were smart enough to only drink water, and they knew the way to their barns or corrals (where they would be fed the next morning). I never heard of a fatality caused by drunks riding (the only injuries were incurred by the drunks who thought they knew better than the horse, who usually wouldn't put up with whatever they were doing, and would assist the "rider" in dismounting - I saw more than a few such "riders" walking/swaying/trying to run along just behind and out of reach of his horse as the horse headed for home - they got there one way or the other. Overall, a lot safer than driving drunk, especially when they'd just let the horse have its head. Sadly, the whole Phoenix area has turned into a major city, the real cowboys (and the ranches) are gone, and one would be crazy to try riding a horse in to town, now.
