A failure of historical imagination (mine). Or, N.C. Wyeth, streetcars, bike racks, and historically-designated air.
I pride myself on having a well-developed visual-historical imagination. What do I mean by that? On the one hand, when I see an historical building or a work of art or a photograph of people from an era before our own, I can make a well-educated guess about its date, and I also have a pretty rich historical context in mind in which to place that artifact. Indeed, I often find myself shocked that other people can't do this. (That's a subject for another blog post.) That ability comes from long immersion in historical fields — I know at least a little about a whole lot of Western history, and a whole lot about some of it — and from concentrated study of art and architectural and costume history, inter alia, but also from a disposition to cultivate a visual-historical imagination.
I'm sure that orientation comes in part from my lifelong love of historical fiction. In my very earliest reading years, I read books illustrated by N.C. Wyeth and Howard Pyle, and when I moved on to reading books without pictures, I continued the habit of "illustrating" the premodern worlds I was reading about in my head.
The flip side of that orientation is that when I am reading about an aesthetic controversy in the past, I generally assume I can visualize the terms of the debate in my head, even if what I'm reading is not illustrated. If I'm reading a debate about clothing or architecture from a hundred or two hundred years ago, I can usually draw on enough of a mental inventory of styles to supply the necessary context.
But knowing about the styles and materials of buildings or dress in the past is a far cry from really being able to picture the complete environment of a place in the past.