In terms of the military accepting liability, or the government controlling the military, I believe the way this is viewed is that casualties are just unavoidable, necessary collateral damage. Possibly in some cases "casualties" are considered part of a desired outcome. There is a book out titled "The Shock Doctrine - The Rise Of Disaster Capitalism" by Naomi Klein in which she makes a good case for the fact that disasters and wars are exactly what big business wants to see, as it means more business for them. So if casualties are a fall-out of the economic juggernaut, that is expected and not such a bad thing if it leads to achieveing the economic objective.

In terms of PTSD casualties, the United States Army deliberately classifies these people as "Personality Disorder" in order to just kick them to the curb, and use the funding to buy more "warm bodies" to throw in to the breach.

Military PTSD casualties will only start getting appropriate and deserved treatment when either: the people convince their representatives in goverment that they will no longer tolerate this, or when big business figures out how to make a financial killing on treatment for PTSD casualties.

Circling back to the military, like all good soldiers, their actions or inactions are a direct result of an institutional culture of following orders from on top.