look like the list is pretty 50-50. I still believe that government workers (biggest employer in the U.S. except Walmart) pays peanuts for the most part. A GS-5 is the beginning of the middle management. The pay grades go from GS-1 to GS-15. Majority of jobs in the government are GS-5 to GS-7. Basically from 2100 a month to 3300 a month. Hardly living off the hog. By the way a Walmart employee makes around 2500 dollars a month....way more than a GS-5 and below.
Their overall number was 20% more for federal employees on the average. There's a column missing on that table: the number of employees in each category. To get the overall average, you need that.
Also, the list has some interesting anomalies, such as the gap in favor of the private sector for aviators. But you figure, most of those federal aviators are young and in the military and can good look forward to lucrative civilian flying careers when they get out.
BTW, NGOs pay even better, especially the international state-supported ones. For instance, I read that, prior to his recent stumble, Dominque Strauss-Kahn was pulling down $450k/yr tax free. That's more than Zero gets paid, and he owes taxes on his pay.