I think I figured out the tax dilemna in Brentwood Borough. Just as a note: Brentwood ranks at or just below the highest mileage rate in Allegheny County. Here is the top 2:
(1). The school district is the largest chunk of this mileage attempting to hold onto its current physical structures of Moore Elemetary, Elroy Elemetary and the ever updated High School. 11,000 residents get to provide all of this for a typical graduating class of 100 students.