Perhaps also contrary to popular belief is that the Amish drink alcohol and love to celebrate with their friends and family. They do not have any specific prohibition against getting drunk.
They also have one convenient technology the rest of us still dream of: self-driving “cars.” After a night of merriment they need to get home safely but that’s no problem at all because the horse knows the way home! They simply climb in their buggy and let the horse take them back, so they can tuck in bed and rest up for another day of work the next morning!
But you are right - it's still safer for them to get home with the horse knowing well enough to not run into the ditch.
Some states only prohibit intoxicated operation of motorized vehicles and it is perfectly legal to operate a bicycle or carriage while drunk.