I must not have made myself clear. I wonder whether a person
who has his printer setup as open could be victimized by
someone outside sending stuff to the open printer.
In my search for open sites I saw that some sites came
up as open and were HP printers. I don't know where they
are, they are just somewhere and open.
Root-
Obviously someone could do that. Damage might be limited by how much
paper is in the printer, or how quickly the owner could react if nearby.
Many wireless printers come with their WiFi set up in ad-hoc mode. HP
also has their "Wi-Fi Direct" mode. You can connect directly to them
unless they have been paired with a WiFi router.
I think what you are seeing are wireless printers that are either
connected by a USB cable instead of WiFi, or are being used with iPhones
that have their internet connection through the phone company.
The owners may not be aware that the printer's WiFi is open! Anyone
that has such a printer should at least set the WiFi to require a
password.
Fred