I've worked in both the public and the private sector and can definitely understand the argument. In my government job it was way easier to slack off and no-one really cared about the results. There was no actual pressure from above to hit targets. You had your budget and it didn't really matter what you produced. Not hitting deadlines was no big deal.
Compared to my normal jobs where there is a constant stress from management to be lean, efficient and hit goals. I hate it but the team spirit is much higher and I probably produce 10x in comparison.