Technology wise, aircraft are already 90+% automated - autopilot does basically the whole cruise phase, pilots are there to do the communication with ATC, manage the autopilot, and be hands on for taxi, takeoff and landing.

From a legal/policy perspective, the aviation industry is held to a much higher standard of reliability and safety than the automotive industry - the AI driven YOLO that companies like Waymo get away with. It’s not just that autopilot systems have to always work, it’s that they have to always behave in a predictable way.