Interesting—I haven't seen that term used that way before. If I encrpyt my customers' private data using a well-publicized encryption method, is it still security through obscurity, simply because they are secrets?
Anyway, the whole idea that the state needs to operate in secret to perform its duties is ridiculous and only serves bad actors. Who would seriously wish for a secret police force anyway? Maybe we should be focusing on preventing and deescalating, through systemic and scalable solutions, instead of masked weekend warriors kicking down doors and shooting people. Also, if you want a laugh - here is a funny story about what happens when you allow the DEA to operate in secret: http://www.thisamericanlife.org/radio-archives/episode/540/a...
I don't know, that's not such a bad analogy. To put it another way, a key is just a really funny way to write down a bunch of numbers, and a key-lock is just a really esoteric number-pad.
People have actually broken into houses by cutting working keys from pictures they took of victims unlocking their doors—so it's not even obscurity aiding the security per se (or rather, it used to be, but then we greatly standardized the way key-locks work.) Instead, it's just concealment, like the concealed face of a credit card in your wallet.