Correct, and they aren't losing money when they sell to consumers that don't need to full capabilities. Yet the tractor itself is already capable (and purchased -- or at least financed which amounts to legal ownership going to the consumer). They recoup their initial dimes in the base cost of the unit.

So JD, which isn't losing money on the "entry level" product provides no actual goods or service for the upgrade, beyond removing the governor. At that point, it's more or less free money to JD -- profit with nothing provided the consumer.