Do printers really have hard disks or any kind of storage in them?

I keep hearing about how insecure it is to use printers to print any kind of sensitive material, such as Bitcoin private keys. Allegedly because they store all printed pages on internal storage . But is this really the case? Isn't this just for big, expensive, industrial printers? And even then, it seems a bit weird to me. Why would this be done in the first place? I have a Canon PIXMA iP2700 purchased 8 years ago. Nothing in its specs seem to indicate that it has any kind of memory whatsoever. Is this unusual?

Question by L. Dones on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.