I think whoever was using the tractor was trying to smooth out some of the muddy ruts on the side of the road.
Only the very intrepid can squeeze their cars through the muddy space between the tractor and the grape vines. Otherwise, backing up is the only option. Fortunately, there is very little car traffic on this road. It's mostly the vineyard workers and a few of our neighbors, and we all know the tractor is there.