War brings out the worst in a people, and while military organizations have discipline, a specified mission, a chain of command, and some form of professional ethic and restraint, civilian support groups are essentially mercenaries, some say war profiteers. They are usually manned by highly trained ex-soldiers, but they operate with spotty supervision and entirely for profit. Limiting collateral damage, long term national goals, and winning the good will of local populations is simply not a priority with them.

From the point of view of the govenments who hire them, they are an economic expedient. Many support troops are required just to keep one fighting man on the line, so outsourcing this activity to private firms allows peacetime militaries to be cheaper and much smaller, and the costs of training, hiring and maintaining these private armies does not appear in the defense budget,and can be concealed in the wartime expenditure. And of course, there is no accountability. If they screw up, there is every incentive for those who hired them to cover it up.

It also serves an ideological role, removing essential functions from government control and funding and allowing them to be parceled out to private contractors for private profit. Basically, it's another form of privatization, finding a way to remove an activity pioneered by public policy with public funds and handing it over to a company which can profit directly from it without having to spend its own money developing the program. The ideological rhetoric tends to conceal the fact that any economies derived from using these contractors is illusory.

But by far, the worst effect of these mercenaries is on the morale of the troops. Imagine a Seabee who has repeatedly risked his life and worked his heart out building airstrips and fortifications on a sailor's salary, suddenly seeing this work taken over by a highly paid professional who rushes in, does a shabby job, and then goes back home safely to enjoy his outrageous salary.

And of course, as these firms become more integrated into military planning, it is inevitable that they will seek out a role in helping to set military policy.

Like I said, war (and money) brings out the worst in a people.