I suppose cities want to use sensitive microphones put up around their cities to detect where the gunfire is originating. Gun silencers would hide such activity. This is the only thing I can think of why they want to ban them.
Up through the 1990s...I just don’t think there were that many silencers out in the general public, or interest in getting them. Over the past twenty years...some fascination has started up, and I’d bet on the number that ATF says....1.5-million in the general public.
I do agree this new technology of ‘listening-posts’ (technology from the Iraq War period) is bundled up and cities could invest money into this, but it’d be worthless if the trend with silencers continues.