More efficient usually means different types of jobs. Take an ATM for example. I'm sure there were those who moaned about the loss of banking jobs when ATM's first started to be used, but banks still hire plenty of people. Plus, now we need people to build, install, and maintain the machines. Somebody still needs to write the computer program for the machine.
Higher efficiency often means that a higher level of skill is required. When I worked at a law firm, there were paralegals there who remembered using a typewriter to complete forms, and that they had to have three colors of correction tape, one for each layer of the carbon copy paper. Computerized forms were implemented, so each person could theoretically complete more work, but that meant that clients could expect a faster turn around so plenty of people were still needed. Plus, it added a requirement for an IT team in the office.
I read a study once that even with all the efficiencies in modern cleaning technology, the average woman still spent the same amount of time as before we had machines to do it all, because higher efficiencies lead to higher expectations. If you can clean your clothes with the touch of a button then they had better be washed every day.
