It's a lot more than that. Yes, a combine or tractor has the things you mention, but they also have complex power steering, computerized control mechanisms for

It's a lot more than that. Yes, a combine or tractor has the things you mention, but they also have complex power steering, computerized control mechanisms for delivering seeds or fertilizer on a per nozzle basis based on yield patterns from previous years, GPS systems, control systems for leveling the vehicle on hills, sensors and measurement systems to control the operation of the engine and evaluate yields, complex differentials to address different stresses on the tractor as it pulls up or downhill or pulls different loads, not to mention all the complexity of threshing and separating grains inside a combine. These machines are insanely complex these days.