That's probably because it's an "illegal" crossing instead of a proper private grade crossing; it's probably just dirt piled up against the outside of the rails and probably some ballast piled up between the rails to keep the farmer's pickup truck from bouncing around too much. The MOW and train crews probably knew that (and may have even known the gentleman in question) and figured "no harm, no foul" as long as it was just the farmer (who was likely wise enough to "stop, look and listen" before crossing, unlike far too many people today) who used it. Nowadays, of course, that's not allowed.