I usually nod or say a quick greeting in passing as I head out for the evening. I've also thanked the guy who refills the soda can dispenser, pointing out that the company runs on caffeine. Each of these interactions takes less than 30 seconds and reminds us of our shared experience on this planet.
I just don't want to disrupt their work or impose that they have to respond back.
Author is describing the second, and it happens pervasively in the upper classes.
Seeing and thanking overlooked people for the work they do takes almost no time if its habitual, yet can potentially brighten someone's day.
Do you extend this to other jobs as well? Is it demeaning to say hello to your boss because she's been hired to spare you the time of managerial decisions? What about the QA folks who've been hired to save you the time of executing tests?