Easy S:
The basic argument is this: "I have been trained by the military to do X, I have been assessed (by military assessment criteria) as competent to do X and I have been doing X for a certain period of time. Much of what I do is similar to what civilian pilots do. Therefore, I am entitled to claim credit for my (military) training for an equivalent civilian pilot licence, rating or certificate; whatever."
On most occasions this is probably true. The recently published conversion report quite rightly allows for military training and experience but requires that an applicant for an EASA licence, rating or certificate demonstrates that he/she is competent to exercise the privileges of that EASA licence, rating or certificate.
The MOD requires the same of civilian pilots on MOD contracts. I fail to see the difference.
BJ