Renting/Leasing doesn't help, because the real cost of failures that can't be fixed is time. Crops need to be harvested in a small window of time, and if your tractor is broken due to a software bug that you're not allowed to fix yourself, and that you're not allowed to hire a third party repair shop that's "unauthorized" by the manufacturer, and the wait for an authorized repair service is weeks, you've lost your entire season's revenue. As expensive as these tractors are, the cost is insignificant compared to the revenue they generate when they're operating.