the least "big government"
I don't know but from all I read about NASA I get the impression that, as good as the engineers are at the one end, the bureaucracy and politics on the other end are just as bad as in the rest of the government. Space X doesn't have to build their components in 40 different states and in order to please 40 congressmen and get the funding etc.
Also, don't underestimate the power of competition. NASA only had to meet some arbitrarily set deadline and in the worst case get chewed up in a congressional committee after the 10th delay or cost overrun. Space X has to beat its competitors on price and service or else it goes out of business.