The trucking industry alone employs ~3% of the entire American population. That's not trivial by any means

I just thought I'd mention that driverless cars can be expected to have a lot of ripple effects. Parking lot attendants; traffic court clerks; insurance claim adjusters; auto body repairmen; the guy whose job it is to calibrate breathalyzers; meter maids; etc. All of these people could face a good deal of unemployment if driverless cars come in.

As far as your larger point goes, I think you make a good point. By looking at AI in a narrow way, Eliezer is giving short shrift to a lot of technological improvements which have the potential to cause unemployment. For example, if a business starts scanning documents and keeping them electronically, it will probably need fewer file clerks and mailroom guys. Does this count as AI? Perhaps and perhaps not, but when people assert that unemployment is due to advances in computers, they certainly are referring to these types of changes.

As far as unemployment itself goes, I also agree with you that even if the theoretical model is correct, there is still surely a lag in reemployment which has the potential to cause disruption. How quickly did the need for blacksmiths drop down to nearly zero? Probably pretty slowly and gently compared to what might be happening now. Perhaps a 50 year old blacksmith would have urged his son to find a different line of work but would have had enough business to see him through.