My understanding is that US government salaries are high because the US private sector pays so well for comparable positions. The US is in the peculiar business of competing with itself, in a sense, or at least with its own economic model.
Private vs. public isn't such a teeth-gnashing, nail-biting dilemma for many other countries, who generally seem to do a better job of mentally separating the two sectors. The general agreement in other countries is that public = stable job, lower pay, higher "public service" calling; private = higher salary, less stability, etc.
Of course, this isn't taking into account countries like China -- where a government position is the best route into cushy, lucrative gigs in the private sector, and in fact, that's often the entire point. (To some degree, this is also the case in the US, at least at the higher levels of public service.) But I digress.