Comment by rurcliped

Possibly because the firmware could be modified, and not print the required yellow dots or other tracking data:

https://www.eff.org/pages/list-printers-which-do-or-do-not-d...

"Some of the documents that we previously received through FOIA suggested that all major manufacturers of color laser printers entered a secret agreement with governments to ensure that the output of those printers is forensically traceable."