A human translator, even when typing at 120 words per minute, cannot hope to approach the processing speed of a computer. On the other hand, he or she is supposed to be familiar with the subject matter and able to recognize certain stumbling blocks where computers often fall short — such as subtle nuances, humor and familiar idioms — so that "out of sight, out of mind" isn't rendered as "invisible, crazy."
Some years ago I made the acquaintance of a young North American — we'll call him Harold — who fell in love with Japan's culture and was supporting himself by teaching English. One day he confided to me that he yearned to change to some other profession.
Harold told me he'd been studying Japanese earnestly and estimated he was up to "about 800 or 900 kanji" — in other words, off to a good start. It just so happened he had obtained a university degree in electronic engineering.