Why would John Deere want to run their own 5G network?
Simple, John Deere is shifting from wired to wireless control. 5G provides a great advantage in equipment control for their factories, but the possibility of hacking and interfering with the workings of the assembly line. It is more secure, more under their control if they install their own network.
It also means they do not have to worry about network loading from other customers. Their capacity is their own.
They have actually paid for 50 Mhz of spectrum in 5 counties where they have factories.