"Last year, the fees that Ontario charged air carriers per passenger averaged $14.50, about seven times those charged at Burbank, more than twice those at Long Beach, 45% more than Orange County's John Wayne Airport and 31% higher than LAX...Lindsey also said Ontario's expenses and staffing have been reduced, lowering this year's per-passenger fees for airlines to $11.73 — although they remain the highest in the region."
The article says ONT was 31% higher than LAX last year but it appears now to be competitive. I'm not seeing how a few bucks difference in PFC make ONT less competitive. IMO the dramatic cutback in flights by the airlines serving ONT are responsible for the higher fares.
ONT is my home airport and it's not uncommon these days to drive past the airport in the afternoon and not see one single plane sitting at either terminal. LAX often has cheaper fares but by the time you add in more expensive parking and the extra gas it takes to drive there it's usually about even. And rush hour traffic makes LAX essentially a non-option for IE residents during much of the work week.