I'm quite sure that every US English desktop keyboard Apple has sold in the past 10 years (I think longer, but don't have one handy to check) has had "Control" and "Option" clearly printed on their respective keys, and "Option" has had a little italic "alt" above it since at least the original iMac days. That's why all the literature uses this convention.
Command, however, has only had the Apple key and the corresponding symbol for as long as I can remember--that one's easy to figure out from the symbol in the menus, but confusing to new users who read "Command-Q" or something.
Say, does anybody out there still get the urge to call it "Open Apple" instead of "Command" or just "Apple"? being an original Apple //c user, there was always open and closed apple (what the heck was closed apple even used for?), and even though the Mac has had only one apple key from the begining, it's always been an open one and I always want to say "Open Apple" even though I catch myself and say "Command" like a good little boy.
Habits learned young die hard.