[q2]

If they are licensed to operate, why they are less secure than human driven planes? It is one more area where automation may drive human jobs away.

May be self-driving planes is next stage of aviation evolution just like drones for military purposes.

[tim333]

Computers are not yet capable of dealing with engine failure on take off as in http://en.wikipedia.org/wiki/US_Airways_Flight_1549 and probably some other system failures. Maybe in the future.

[danielbln]

There was an incident just last November where the flight systems put a A320 into a nose dive towards the ground and the pilots had to restart the board systems in order to pull the machine up.

[q2]

My understanding is, the more hardware/software reliability,durability increases, the less may be the need for humans to intervene.

If we look outside, technological trends and intents of organizational leaders are in the direction of more automation and lesser human dependence.