There is currently an aviation-history tag with 20 posts on it, and no history tag or other tag with history in the name. Why? This whole site is about aviation, it seems like all the tags should be assumed to be related to the site. The aviation bit seems redundant. What am I missing?
This seems like a rather pedantic argument to me. It doesn't cause confusion, and if you type in "history" as a tag, you get auto-complete for aviation-history. You're right that, in a sense, every tag is implicitly "aviation" already, but unlike most of those tags, the phrase "aviation history" sounds normal and natural as opposed to "aviation IFR" or "aviation pilot."
Essentially, my point is that it doesn't matter, but if enough people want it changed, we'll change it.