Having some knowledge on the unseen discussion about Daniel Carr's fantasy, his "coins" fit into an area where there are loopholes in the law. Since the items he has produced (or produces) are not copies of legal tender coins and are not sold to defraud anyone, the government is afraid that any case would not hold up in court. Even though Carr's work is in the fringe of legal, they do not feel that they can make an example of him. Treasury is watching and waiting for him to cross a line before doing anything else.
Afterword: How is the HPA not an effective law? What would you like see changed, forgetting the political realities?
One of the problems with this discussion is that it is using the text of the original 1973 law. It has been updated. One of the updates is the Collectible Coin Protection Act of 2014 that allows the prosecution of those distributing/selling counterfeit coins. It fixed the Hobby Protection Act which said that the government could only prosecute the producers of the coins. CCPA also allowed the government to add to their regulations (15 CFR) to make the platforms liable after being informed. This is why eBay stopped allowing copies even if they were marked as "COPY" on their site. It was just too difficult for them to control.
If you want tons see the full legal text of the Hobby Protection Act will all amendments and changes, it is under 15 U.S. Code Chapter 48 and can be found https://www.law.cornell.edu/uscode/text/15/chapter-48