My experience is that in the public sector, things often move slower, but the range of productivity seems to have a significant overlap with an average large company. I think the cost of nobody believing in what they are doing is an underappreciated drag on many private sector workplaces. The fact that failure is not an option in the public sector has several oft repeated negative consequences, but it also means that you have a reason for coming to work and making an effort, (other than not starving) even if nobody appreciates it, management is terrible, working conditions are lousy, pay is poor, co-workers are idiots, etc. That counts for something towards effectiveness, if there is a core group that hasn't descended into nihilism.