Sometimes, for example

https://duckduckgo.com/?q=docucolor+"not+visible+under+norma...

We originally found that in German,

https://duckduckgo.com/?q=docucolor+"unter+normalen+bedingun...

However, I don't think that most printers currently disclose this, at least for sales in the U.S.

It's hard to imagine what law this would break.

By the same token, what is compelling them to do this? A sense of patriotic duty? The kindness of their hearts?

There's a lot of work that would go into designing, implementing, and testing this. Then you've got logistics in manufacturing. That's time and money.

> By the same token, what is compelling them to do this? A sense of patriotic duty?

The GSA Schedules: https://www.gsa.gov/portal/content/197989

The original motivation seems to have been a deal between a printer industry association and a central banks' association, perhaps as an alternative to threatened legislation, although we've never been able to get ahold of the details of that deal.

What law do you suppose this breaks? Illegal isn't defined as "something I dislike."

privacy / trade laws / 14th amendment equal protection / due process

It definitely does not feel right that some non government entity is deciding to encoding personally identifying information about you without public oversight.