I've read it, and it is mimicking that through idiotic and restrictive End User License Agreements. For the software.
There is no explicit clause that forbids tinkering with the hardware, but that seems to be enforced by the software. As in, change a part that has a microcontroller and it won't work without a John Deere technician coming and authorizing it.
Besides, if I read paragraph 13 correctly, the owner of the tractor has to indemnify John Deere and its dealers against all and any lawsuits, even if John Deere or the dealer is at fault for the cause of the lawsuit. That goes beyond everything I've seen in software EULAs so far. Those usually demand only indemnification against lawsuits that arise out of actions by the owner.