Not only are you estimating the astounding ingenuity of farmers it's not hard to make a convenient interface for a jailbreak. Often times even replacing a tire

Not only are you estimating the astounding ingenuity of farmers it's not hard to make a convenient interface for a jailbreak. Often times even replacing a tire is so expensive on a tractor after paying the highwaymen their fee the probability of bricking the tractor is probably not even factored in. John Deere more-or-less bricks your tractor anyway. So, arguably, it's no loss if you brick it given the alternative could be not putting food on the table because you spent 3 years of checks on repair or you'd have to buy a new one anyway.