"an Apache feature I didn't know about" - looks like mod_speling, one of those old-school features Apache has from back when the expectation of a website was th

"an Apache feature I didn't know about" - looks like mod_speling, one of those old-school features Apache has from back when the expectation of a website was that is was just a bunch of user's public_html directories exposed as /~username/, designed to deal with things like case sensitivity and typos in URLs.