ONT has higher operating cost and more employees than some regional airports around the country because it has two runways, a 24/7 cargo operation, and two brand new passenger terminals.
Comparing the number of employees is truly meaningless without taking into account the size of the facility. SAN may have 355 employees but it also has only 1 runway and tiny cargo operation. ONT has 2 runways and 24/7 cargo operation. When you put it in relevant context, ONT's 387 employee actually seems under-staffed given the huge disparity in the size of the property compare to SAN.
Most of the airports cited in the report do not have 24/7 operation, only a few has two active runways, and majority has not had significant terminal facility capital project in the same scale as ONT in a while. Some of the airports cited in the report are also joint civilian-military facilities which means the civilian airport authority/operator is not responsible for the entire cost and staffing of maintenance of the entire airport property.
Of course if LAWA didn't permit 24/7 operation, or build the 2nd runway, or the new terminals, that would be used by conspiracy theorists to show LAWA let the place fall apart without capital improvements.
You can't complaint about high costs per passenger enplanement and ignore all the investments LAWA made to ONT. LAWA invested in the airport to support 2008-level passenger activity. To even suggest that LAWA somehow undermined the airport is pretty ridiculous - they did the opposite... Over invested in ONT by a long shot. The total operating cost of ONT is not high compare to other similar airfields... it's only when you divide it by the declining number of passengers, the numbers stick out. How about if we divide the operating cost by number of tons of cargo? I'd imagine SNA will look very unfavorably in that metric. I guess those guys are doing a horrible job?
Or operating cost divided by number of parking lot spaces? ONT is going to beat every airport in SoCal using that metric.
Or operating costs divided by number of Taco Bell within 20 miles radius? I don't know which airport will be the cheapest but ONT probably has a good shot.