Sanitation workers have one of the most important jobs in modern society, yet they are consistently undervalued and treated like shit, and I for one have never understood this-but bigots gotta bigot, I guess.
You see this in other odd ways as well. One that I just noticed the other day-Utility linemen are treated as respected professionals doing a dangerous job, and are compensated well. The crews that maintain the utility right-of-ways by trimming trees (using much of the same equipment, plus chainsaws, chippers, and dealing with dangerous falling debris), are poorly paid and complained about. These guys keep the lights on as much as the linemen do, yet are not as valued. You see this kind of thing all over the place. Humans apparently love hierarchy.