One of the beauties of leasing... you don't own the problem after warranty expires. With new technology and the extreme advances, you'd be hard pressed to keep up with things in production environment and service it yourself. The electronics and software are just to complicated for most folks, let alone the cost of purchasing or renting the diagnostic equipment.
It's all been figured into the cost of the machine and it's expected lifetime. Who's gonna purchase a 10 year old computer for their house? Who's gonna purchase a 10 year old tractor that's basically a computer now? What's going to happen to 10 year old off-lease tractors? Constant upgrades maybe.