In modern usage "Copier" is a polite term for "Scanner and laser printer in a single box, with a usurious support agreement" (seriously: I dealt with a Canon unit that, despite having full network connectivity and print capability, didn't offer support for any printer languages, like PCL or Postscript, without an additional license that cost more than a midrange laser printer...)
They can copy stuff; but they can also do things like create PDFs, automatically email scanned documents, even do LDAP/Kerberos auth against an AD to drop files directly into user directories.
Some of them do have OCR capabilities (to generate PDFs that have a proper text plane, usually). In this case, though, the problem was with the compression algorithm, which performed a somewhat OCR-like operation; but which was not counted as 'OCR' for the purposes of turning OCR off before testing.
Worse, Xerox knew about the issue. The manual actually notes that 'occasional character substitutions may occur'. And they shipped it. A dyslexic copy machine.