There are many examples of the wastefulness of government spending. In light of this, I will name a few.
First, often times the government does not hire the right people. In other words, many of them are not as capable as people in the private industry. For this reason, jobs are not efficient.
Second, there are many people who have government jobs, who play the system. For example, there have been many investigations of late of how working are "playing" the system. They get paid overtime with little work and gain benefits without ever showing up to work. This might seem far fetched, but this is really happening. I will add a few links.
Third, there are many fraud cases. For the example, there are now scandals in the TARP payouts and hurricane Katrina payments. The list goes on and on. Big government cannot run efficiently.