But we want 2013 healthcare, which is far more labor intensive. I have a herniated disk. In 1950, a doctor would spend an hour telling me I'd have to live with back pain for the rest of my life. In 2012 many doctor hours were spent on my MRIs and laparoscopic surgery. Net result is that my deadlift is now about 285 - nothing impressive, but not possible in 1951.
So the short answer is that including healthcare, we work more because we want more. Many of the things we want more of require more labor in 2013 than in 1950.