It's technical jargon. Scientists used speak a mishmash of Greek and Latin, since those were common among educated people. That hung on for longer than was realistic, but it became a kind of slang for group recognition.
This department was named in the 1880s. They probably would just call it the Apple Department today, though I admit I still like the tone that sort-of-Greek-or-Latin rings.
You don't have to go through all the globals, you just have to get the caller's namespace, which is fairly simple. See e.g. https://stackoverflow.com/a/6618825/27426
For this reason, I think it's not true that this absolutely had to be a language feature rather than a library. A template class written in pure Python could have done the same lookup in its __init__.
