Sort of inspired by the 'guess what's been invented again' thread...
Some years ago, I was unlocking my winter bike from outside the supermarket and an old chap came up to me and said "has that got a hub gear?"
Yes, I said. And he went on to tell me that he'd had 3spd hub geared bikes when he was younger, and how good they were, and how he'd once done some thinking and reckoned it might be possible to get as many as 5 gears into a hub.
I had to tell him that, yes, mine has 8... I didn't mention the existence of Rolhoff.
When I was doing cycle promotion work, and try out roadshows, there were large number of people astonished by cycle technology that seemed commonplace to me. Even on forums, there are keen cyclists who seem to have missed out on certain areas of cycle technology.
I suppose it's just what you're exposed to - it was only due to a post on here that I found out that there's such a thing as an electronic handbrake on modern cars.