Such was the regularity of defence cock-ups that, 10 years ago, the government established the "projects of concern" watch-list. This list of troubled projects – those that are far later or costlier than planned, or that don't work as they should – is overseen by the Defence Department as well as the Auditor-General. It is an unambiguous attempt to shame those involved in the projects into delivering what was requested, when it was scheduled and for the money agreed.

It may seem odd that a government department would humiliate itself publicly in this way, but that was never the list's purpose. For while the department, its public servants and the defence minister of the day tend to cop the blame for procurement bungles, the fault regularly lies with Defence's business partners.

No other department is as dependent as Defence is on using private-sector contractors to do its core work. As Australian Strategic Policy Institute senior analyst Marcus Hellyer told this newspaper recently, the department's ranks of contractors have increased to the point where, in some areas, only a thin layer of public servants oversee a project run entirely by private-sector labour. This echoed the concerns raised last year by the department's then secretary, Dennis Richardson, who expressed frustration that Defence "employed" more consultants and contractors than it had staff.

This week's revelations about contractors working on Australia's largest military procurement – the $50 billion future submarines project – will not surprise Defence public servants. The Canberra Times published internal Defence allegations that contractors had engaged in nepotism, sought to hide conflicts of interest, breached spending rules and, when the department raised these concerns, failed to respond transparently. One internal memo put it plainly: "Obtaining accurate information in relation to [the submarines project] has been difficult for a number of years, primarily as a result of an unwillingness to provide clear responses on contractual arrangements."

This problem goes well beyond Defence. The government will always have less control of workers whom it does not employ directly, because private-sector labour is not subjected to the same laws governing recruitment and ethical conduct that public servants operate under. Nonetheless, there is a clear desire in the Turnbull government, articulated most often by Public Service Commissioner John Lloyd, to rely more on employees engaged for specific, short-term tasks. This will no doubt be a focus of the government's independent review of the public service, announced on Friday.

There are benefits in using contractors, but the latest submarines scandal reminds of us at least one of the weaknesses.