This isn't surprising, because devs have a tendency to focus on the hard bits of coding as being their work. Why not, right? It's probably the most satisfying too, so we forget the bits where we document, explain to colleagues, organize, etc. Don't forget that a lot of "not working" such as browsing a certain orange-and-beige website actually IS work as well: you wouldn't be updated on what's going on in the tech world if you didn't read some new things regularly.

However consider that there's entire classes of people who never do anything as satisfying as coding during their day. All they do is communicate in some way: making powerpoints, schmoozing with customers over lunch, sitting in meetings to discuss what the business should do. Typically you'll never find one of those people saying they don't do much. In fact, many of them feel compelled to sit in the office - face time - to look busy. If you were to narrowly define their work like I've done with software devs, many people would end up with maybe a couple of hours a day, mainly reading some docs to decide what their business unit should do.