Is it? In my career, over 20 years by now, I've not seen that one often. When it happens, management has to be on vacation too, as it's not that hard to see that someone is doing all the work. I have seen this continue just once. It had to do with the place having very poor pay. Management wasn't firing the slackers because that's all they could hire at their rates. The hard working engineers just weren't wise enough to realize that they could often do a bit less work for a lot more pay somewhere else.
What is more common is that effort levels are similar within the same department, but wildly different across companies. I've worked at places where people considered themselves slackers when they were doing 60 hours plus on call time. I've also worked at others where entire teams did about 2 hours of actual work a day, and the rest was spent on long lunches, ping pong and retro consoles.
