Military medicine is not-for-profit while civilian medicine is profit driven. So is it really the fear of liability driving all the tests? Or the money that doctors make by prescribing them?
Doctors make no money from ordering an extra test. They may save themselves boat loads of time that would be spent in deposition, trial, negotiations should a missed diagnosis be litigated.
There is also a study that shows a slight mortality benefit to defensive medicine. But from a public health perspective how do you charge extra on Insurance for everybody to save a small number of people?