Suppessors are a common shooting accessory in many European countries because they do limit the noise for shooters and bystanders. And they are used with ear PPE while shooting. European shooters are often amazed that supressors require a special tax stamp for each unit in the US for something that they consider a basic safety device.

But what if, what if... you combined both, instead of an 'or' situation?

Good god Jameson, you're off the charts with the ideas this week!

I fail to see how a suppressor only being useful as an accessory for shooting doesn't make it a common sense accessory (for shooting). They're common sense in the same way that wearing a mask when you're sick is common sense. A mask helps prevent you from getting other people sick, it doesn't protect you from getting sick. Wearing a mask isn't "not common sense" because it only works while you're sick and not all the time.

It's like scraping snow and ice off your car. Cleaning your windshield will let you see when you drive, but cleaning off your roof will prevent a sheet of ice from slamming into the car behind you on the highway when the wind catches an edge, or will save you from having it slide down onto your windshield the next time you slow down and blind you. Calling a snow scraper a common sense accessory isn't a stretch because a lot of the world never sees freezing temps or snow. Tools are made to be used in context, and within that context it can be common sense to use them for that purpose.

I can't speak to other countries, but in the U.S., the greater part of our tax code is made up of tax credits and penalties meant to influence the behavior of individuals and companies. That's the result of our government not having other adaptable mechanisms for levying fines.

Ear plugs/muffs do the same thing

I reject the premise of your argument.

Ever use a set of bone conduction headphones? These sit on the temple, in front of the ear, and conduct sound waves directly through the bone of the skull. Wearing earplugs does not reduce the effectiveness of such headphones. Bone conveys sound waves exceedingly well. You can damage your hearing with bone conduction headphones, even while wearing earplugs.

The reality is that earplugs or earmuffs are not adequate for fully mitigating the harmful impulse noise of common firearms. Injury is lessened by ear protection, sure, but it is not eliminated. No amount of ear protection can prevent a sound pressure wave from being conducted to the cochlea by the skull bone. Earplugs and earmuffs limit sound passing through the auditory canal; not the skull itself.

Silencers reduce the harmful sound pressure wave before it can be conducted by bone. As such, they are much more effective at mitigating harm.