A philosophical and moral preset: humane and mechanical compete inside a human being. Being a machine is bad, because machine is dehumanizing, machine inside a human being destroys his/her human core. Yes, many thinkers envision some kind of ideal synthesis, i.e. a person can work as an efficient machine for 8 hours – and then again become human with all his/her merits. Unfortunately, for some reason, this does not happen in reality.
By default, “efficient” means with “limited efficiency”. Because one cannot be efficient in everything.
Two main characters – human being and machine. Machine has been poorly described in philosophy and culture, human being – even worse; both images are complicated. But they are opposite: usually, a human wouldn’t like to be turned into a machine. It is difficult to separate these images: a human being has mechanical in it, while machines are acquiring more and more human features. In general, a human being is defined by a free will and feeling of empathy – qualities, presumably, unattainable for a machine; at the same time, these are the simplest categories of differentiation.
(It also is possible to include Godel’s incompleteness theorem: in this case a free will is an element that cannot be proved. By the way, this element can well be the soul.)