There are some details left out here. Wilcox Co. has 888.68 sq mi of land. Falls Church has 2.0 sq mi of land. Falls Church is a small bedroom community located near the capital, Pentagon and endless defense contractors in the area. While it may be treated as a county by the Census it does not have the land mass of most counties. Since most of the highly paid government employees work in and around the capital it should not be a surprise that they would locate in a small city where you can walk to restaurants and bars but still have a small town feel in the neighborhood. The D.C. area is also home to many large associations & nonprofits which also pay well for higher level positions. This compared to industry jobs in Wilcox County which include a paper mill and a copper tubing plant.
Where ever you stand on the issue of Gov't dollars going into schools I think the comparison in this editorial is NOT apples to apples.