In my experience, the airlines do their own policy, which can be usurped by the pilot. I found some airports, I guess because of large number of us, FED LEO, flew out so often, it was simple, without a letter...just check in early, I.D. and declare, no problems. But this was rare, most places it wasn't worth the hassle. By the book, we needed letters from the boss, and official business. As to other issues, there are incompetent civilians and LEO's. But the LEO has at some point qualified in the handling, use of, policies governing, etc. of firearms...a known quantity with credentials, as opposed to ordinary citizen. Both do wrong, and should be dealt with accordingly, not everyone for one's crimes. This country's commander was/is a drunk and cokehead, he's still in charge. I wouldn't worry about the occassional cops that go bad. As far as "highly trained" air marshals..a young guy who used to be my insurance agent signed up with my fed agency, finished the academy, then signed on with air marshals...not experience in anything but bring up insurance policies on the computer...another female agent, who was a poor shooter, is now keeping you all safe in the air (good luck). It happens.