I was under the impression that had already been done. Much of the time a person would have to ask for a stamp. A good example is I got a passport when I turned 18 back in 2008. When doing so I checked the box to get a passport card with it. When I later traveled to Canada and the Caribbean or what not the Passport card is accepted (also works for Mexico but I never went).

There is no place to stamp a card (basically a federal drivers license size for your wallet)

So… It couldn’t have been a formal requirement since at least then