Yes, it'd be lovely if everyone used the term correctly...but a large percentage of users do not.

Googling SFTP is actually very heartening--it takes quite a lot of searching to find anyone using the term incorrectly. This wasn't always the case (and the hearts and minds of the non-technical masses takes a lot longer). We still see at least 50% of our customers saying "SFTP" when they mean "FTPS" (and we don't support any of the proprietary FTP-with-encryption protocols).

I think part of our users confusion comes from the fact that the server that provides SFTP service is called sshd and the server that provides FTPS is called proftpd. Obviously, FTP is right in the name of one of them, so that's where all FTP comes from! System administration is hard.

It seems that there is no so much confusion. Maybe you've had bad luck and met a bunch of uninformed people, then you think that the misunderstanding is more common than it is. My experience is also that everybody I met knew what SFTP is.