The tractor can always be driven by hand. Tractors have not literally "ground to a halt". The systems that have failed are those using GPS with differential co

The tractor can always be driven by hand. Tractors have not literally "ground to a halt". The systems that have failed are those using GPS with differential corrections, which achieve ~2cm accuracy for 'precision agriculture' (tractor auto-steer, making efficient use of chemicals by only spraying them precisely on the plant, etc) The degradation is they now only have normal GPS which is accurate to within a few meters - but that's useless for precision agriculture.