Most farmers believe that rural life far surpasses urban living. (Most farmers believe that rural life surpasses urban living by a lot.) His intelligence far exceeds the average. (His intelligence exceeds the average by a lot.)

"Far" in this sentence means "beyond" or "more than." In this context, "far" doesn't mean "so." "Far" is used to emphasize how farmers feel about rural life compared to urban living but isn't required for the sentence to make sense or "be correct." Without "far" in this sentence, the meaning would be almost the same.

"far _____" here is referring to a high degree. The famers believe that rural life is much much better than urban life.