Many people judge jumping off a bridge while tied to a large rubber band to be very risky. They believe that the probability of getting hurt is very high. This thought is consistent with what has been learned of people's perception of risk. Individuals usually assign higher risks to unfamiliar activities. The reverse is also true.
Individuals assign lower risks to familiar activities.
In addition, people are generally not very accurate judges of risk anyway, overestimating some situations and underestimating others. These tendencies are not in the farmer's favor. A farmer who uses a piece of equipment for a length of time is prone to thinking that the situation is less dangerous now than it was when he first started using it. While the farmer has more experience with the equipment, that experience does nothing to lessen the intrinsic danger of the machine. In addition, the machine may not be very well maintained, which would actually make the machine more dangerous to use.