The technology exists to fly a large passenger aircraft from A to B without a pilot on board.
Not sure how correct that statement is.
How does autonomous aircraft fly through thunderstorms?
How do autonomous is aircraft fly to non ILS aerodromes or better still a no instrument approach aerodrome?
How do autonomous aircraft land in gusty 40knot crosswinds?
How do autonomous aircraft land with shifting winds?
How do autonomous aircraft handle data input failures or data corruption?
(ie airspeed indications are no longer reliable or false sensory inputs ie stall warning goes off incorrectly)
This small list of problems will just be the beginning of what needs to be solved before we have the technology for autonomy.