I almost always use my badge to get through. I have had 2 times where they wanted a government issued ID instead for one bullspit reason or another (not in uniform or something like that). Once in MSP, once in DEN, so not exactly tiny airports. I think both times I tried arguing with them a little ("I've always been told that this is supposed to be enough for you...") and eventually show them my license while telling them that I'd appreciate it if they would check with their supervisor when they have a chance to.

A few months ago I had training at DEN. For the first day I made (and later cancelled) a NRSA listing just to give me a boarding pass to get through, and also talked with a supervisor to get an idea of what the official policy is supposed to be. He told me that an airline badge alone (not even a boarding pass alongside) is supposed to be enough (I've given up on that one and just give them that from the start). When I told him that I've been told my airline badge was worthless at the ID check, his jaw kind of dropped. The rest of the week I went through with just a badge, but I also wasn't carrying any bags with me, either.

Still, better than when I tried using the TSA's contact form to ask the actual policy. My response given was essentially "thank you for asking why airline employees don't need to show ID..."