These days, in my not all that humble opinion, the biggest thing keeping technology from removing the operator is that we already do not have or need enough jobs for everyone that wants to work. Once we do away with forklift operators, who will be left to pay into the 'unemployment insurance fund'?

Just as "globalization" [read as -forklifts- and material handling advancements enabling the movement of mass quantities of goods over long distances with very little {expensive} manpower] has made it possible to have {very inexpensive} foods and goods from all over the world to all over the world, but does not really require as many people working full time to provide those goods. Just as forklifts have eliminated about 80% of the longshoremen jobs (per pound mile of good transported in [say] 1939), if we did without operators (just like we/google will be loosing all taxi drivers in about 10 years with self driving cars,) we would loose another load of jobs with 'the increase in productivity' that will come with totally operator-less powered industrial trucks. but that seems to me that it is coming.
(see Ray Kurzweil's books "The Singularity Is Near", "The Age of Spiritual Machines" and "The Age of Intelligent Machines")
"We will be the Borg, you can try and resist,,, but it is futile"