Not an expert here, but I recall reading that certain European countries (Spain???) allow liability to be put on the autonomous driving system, not the person in the car. Does anyone know more about this?

That is the case everywhere. It is common when buying a product for the contract to include who has liability for various things. The price often changes by a lot depending on who has liability.

Cars are traditionally sold as the customer has liability. Nothing stops a car maker (or even an individual dealer) from selling cars today taking all the insurance liability in any country I know of - they don't for what I hope are obvious reasons (bad drivers will be sure to buy those cars since it is a better deal for them an in turn a worse deal for good drivers), but they could.

Self driving is currently sold as customers has liability because that is how it has always been done. I doubt it will change, but it is only because I doubt there will ever be enough advantage as to be worth it for someone else to take on the liability - but I could be wrong.