It's not like they had other work to do; they just don't want to do any work at all. They would rather stare into space (thinking deep thoughts? I don't think so ...) than help out. I don't understand this. For me, to be at a job and have nothing to do is awful. "Lack of work to do" is one of the reasons I quit my last job (and jobs before that).
I've worked with these people before, in both white- and blue-collar jobs. And they never cease to dumbfound me, or to annoy me profoundly.
Grumble, grumble, grumble.