Indeed, the GA autopilot systems are pretty simple: keep wings level, altitude hold, vertical speed hold, etc. On the other hand; you can take a lot more risks in your plane that will cost the insurance company a lot of money -- tailstrikes, flying into IMC, flying while sleepy, etc. If you total your Piper Cub, that's going to cost the insurance company a lot of money. If you total your Prius, that's cheaper.
On the other hand, it's a lot hard to get a pilot's license compared to a driver's license. (What are the requirements for a driver's license these days? Having a pulse? No, I don't think they check for that...)