Usually there are after-market modifications (like, just take the muffler off) done which make the sound louder so it’s kinda moot that they include the make and model of the presumably legal production vehicles.

I don’t know if the loud-exhaust bikers are correct about the facts but I do know it’s pointless to try convincing them otherwise; if they genuinely believe it’s safer, from their perspective you’re just demanding that they make an unsafe decision for your personal comfort. Not gonna happen.