[1]https://www.eff.org/pages/list-printers-which-do-or-do-not-display-t
   racking-dots

     (Added 2017) REMINDER: IT APPEARS LIKELY THAT ALL RECENT COMMERCIAL
     COLOR LASER PRINTERS PRINT SOME KIND OF FORENSIC TRACKING CODES, NOT
     NECESSARILY USING YELLOW DOTS. THIS IS TRUE WHETHER OR NOT THOSE
     CODES ARE VISIBLE TO THE EYE AND WHETHER OR NOT THE PRINTER MODELS
     ARE LISTED HERE. THIS ALSO INCLUDES THE PRINTERS THAT ARE LISTED
     HERE AS NOT PRODUCING YELLOW DOTS.


   I have a theory as to why. CALEA allows the government to compel "a
   manufacturer of telecommunications transmission or switching equipment"
   to modify the equipment. Under that or a similar law, printing
   manufacturers are compelled to put tracking information onto paper.

References

   1. https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots