It appears that New Jersey’s plethora of municipal governments is the key factor for the high rate of property taxes. The costs to run each of these disparate operations is costly. Here are the facts:

New Jersey has 565 municipalities
New Jersey also has more than 600 school districts
New Jersey also has more than 600 school superintendents
There are the 21 county governments and their bureaucracies
Public worker salaries and benefits are very high in New Jersey
The high cost of goods & services throughout New York-New Jersey-Philadelphia regions

Two Examples:
Bergen County
Bergen County has 70 municipalities and 70 fire departments.
Bergen County has about a tenth of New York City’s population but more pieces of firefighting equipment than New York does.

Maryland vs. New Jersey
Maryland, which is about the size of New Jersey, ye it only has 157 municipalities as compared to New Jersey’s 565. Maryland’s median property tax bill is $3,305 compared to New Jersey’s $7,905.