your john deere also costs 10x (100x?). accurate gps isn't cheap. here's one of the cheapest chips that gets cm accuracy https://www.swiftnav.com/store/gnss-se

your john deere also costs 10x (100x?). accurate gps isn't cheap. here's one of the cheapest chips that gets cm accuracy https://www.swiftnav.com/store/gnss-sensor-volume-orders/piksi-multi-gnss-module https://www.swiftnav.com/store/gnss-sensor-volume-orders/pik... add >$500 to their BOM is probably something they want to avoid