Shutter sound was implemented by Verizon and others to "prevent" you from taking pictures without permission. Since there is always a sound people around you will know a picture is being taken. It's a stupid rule but there was a lawsuit or something a while back.
Sent from my XT1060
Yeah, it's something that's been debated for a while now in different countries. A few years ago, a bill was introduced in the U.S. House of Representatives: H.R. 414 - Camera Phone Predator Act Alert. It never made it out of Committee, but some carriers and manufacturers still want the shutter sound active.