Tractor hacking is growing increasingly popular because John Deere and other manufacturers have made it impossible to perform “unauthorized” repair on farm equipment, which farmers see as an attack on their sovereignty and quite possibly an existential threat to their livelihood if their tractor breaks at an inopportune time.
Source: Why American Farmers Are Hacking Their Tractors With Ukrainian Firmware – Motherboard
A license agreement John Deere required farmers to sign in October forbids nearly all repair and modification to farming equipment, and prevents farmers from suing for “crop loss, lost profits, loss of goodwill, loss of use of equipment … arising from the performance or non-performance of any aspect of the software.”