Fame
The sad truth is most people only notice how their machines are running when they're running badly or not at all. Good technology is so integrated into our lives that we just expect it to work like magic. Millwrights and other technicians know that it's not magic, but rather the result of a lot of hard work and clever thinking.
That's not the kind of thing that'll get you a parade and the key to the city, though. Millwrights fall into the "unsung hero" category on the fame scale.
You're not going to be gracing the tabloid covers anytime soon. But who wants the tabloids speculating about their weight, anyway? Talk about nosy.