There are multiple safeguards for planes that don't work for self-driving cars. First, they're not physically inspectable by every Tom, Dick, and Harry. This m

There are multiple safeguards for planes that don't work for self-driving cars. First, they're not physically inspectable by every Tom, Dick, and Harry. This means it's easier to obscure interfaces and other potential areas of attack. Not state-actor proof, but probably ISIS-proof. Second, they only get software updates while parked at an airport, so it makes MITM attacks harder (though not impossible). Third, they're in the air where death isn't a sudden movement away. Pilots can override the system and fly it manually. Fourth, they're heavily monitored with errant flightpaths reported to militaries around the world (to stop another 9/11). We have none of these safeguards for self-driving cars and there are going to be hundreds of millions of them.