Gun Control Reform Activism

In other European countries, they are illegal for civilians.

http://en.browning-blog.eu/can-i-use-my-sound-moderator-abroad/

A good article about the subject in the WP:

"Are firearms with a silencer ‘quiet’?"

https://www.washingtonpost.com/news/fact-checker/wp/2017/03/20/are-firearms-with-a-silencer-quiet/?utm_term=.3cc1e4c88ca7

Frankly, I think the article in the OP contains errors and misconceptions. A high powered rifle with a suppressor is still louder then a jackhammer. While wearing hearing protection is good, it's far better to be wearing hearing protection while shooting a gun equipped with a suppressor.

This is what ShotSpotter says about detecting suppressed gunfire:

"16. Does ShotSpotter detect gunshots from gun silencers?
In regard to gun silencers it is more accurate to call them suppressors as they suppress the impulsive sound of gun fire not wholly eliminate it.
We have successfully if not inadvertently detected confirmed suppressed gunfire within our existing deployments.
Although we have not formally tested the theoretical impact to our system we intend to do some targeted testing in the near future. We believe we will have various options ranging from increasing our sensor array density to developing software/firmware to address the detection of suppressed gunfire if it were to become a widespread issue."

http://www.shotspotter.com/system/content-uploads/ShotSpotter_FAQ_June_2017.pdf

It's easy to make a homemade suppressor and there are numerous youtube videos and articles on the internet giving detailed info on how to do so. Flashlights, oil filters, 2 liter pop bottles (for 22s), PVC pipe, electrical conduit, sprinkler risers, cardboard tubing and so on are common materials for making a homemade suppressor.

IMO, the main reason criminals don't use them now is not because they are illegal unless they are registered and one pays the $200.00 tax but because they are of little use except in a few select criminal acts. And a handgun with a suppressor, even a legal one, is much harder to conceal.