Yeah, that does seem pretty strange, just like you said - it seems like everyone should know at least what knitting IS, even if they know nothing about how to do it.
However, I think it is just so extremely cool that you're a trucker/knitter. Just that you can go to truck stops and knit and other truckers and inquisitve, wanting to learn more about the cool stuff you're making. And if you hadn't been knitting there, that poor girl may have NEVER been introduced to knitting - that's tragedy if I've ever heard one! A lot of props for you, awesome