The commenter didn’t spell it out for some reason, but he or she means family members and friends of city employees. They use various tricks to get free parking even though they shouldn’t, and as they aren’t official city employees they won’t get reimbursed for congestion fees and their scam will become more expensive.

Other police, mostly, but also NYFD, teachers, pretty much anyone who puts an official-ish looking placard on their car.

Or sometimes just some stickers from the various police quasi-unions in the tristate area.