Modern farm equipment is designed with safety in mind. Contemporary tractors will all come with roll-bar technology built into the design of the vehicle. If farmers roll their tractor they will be protected. If you are an experienced farmer who has an older model of tractor that doesn't have a rollbar, you may not feel inclined to get one because you feel that you will never have an accident like that.
Chances are that many experienced farmers will never have an accident like this. 

However unforeseen circumstances arise, and the experienced farmer may not be the one driving the tractor.--------------------------fanfanfanfanfnafna