Expecting a programmer to come into an office, sit in front of a computer, and productively work for a total of 8 hours, is utterly and completely unrealistic, in the typical case where the work is not interesting.
And since the interesting work is typically done for free(open source), the only way to get paid to work on software is to work on either really difficult, or really uninteresting problems(often both).
Yet, there they sit, all day long.
In individual offices, or in full-height cubes, they can feel free to take breaks, but in the modern open office jungle… continuous development, continuous integration, and with everyone waiting on someone for something, the collective eye bears down continuously on everyone’s screens.
If you look around, most people are just blankly staring at their screens, because that can be sustained for long periods of time. But, actually, they’d probably be more productive overall if they could spend half or more of their time playing.
Of course, their machines and networks are locked and monitored, so that’s an additional impediment.
So there they sit, or stand, staring blankly, quietly, at work they’ve lost focus on hours ago, because it’s the only safe thing they can do.