I can see having a problem with consultants, we all run into that. I was thinking more about working people. The reason being that a contractor does not have to keep staff when there is no work or can do other jobs to keep their crew and equipment busy while government ministries do not have this option. My experience with MoF was a lot of engineers that nobody in industry would want or could afford. Mostly they changed their minds so often that you could not do a job on contract unless it was strictly unit prices or you had to work on hourly.
I doubt that highways could do their maintenance cheaper in house than by contract. Even now they demand far too much irrelevant paper work and have way too much staff to over see it. The other problem the ministries face is that they cannot fire incompetent or lazy staff.
You know the myth of private sector efficiency was dispelled at least a decade ago.It can be demonstrated and is as we speak that what is efficient to the private sector is inefficient to the public sector. The two have decidedly different metrics of efficiency. Here on the edge of the modern eras second economic abyss known as the new great depression many people give little credence to talk of private sector efficiencies. Fraud is often confused with efficiency.