Originally Posted by Slug
It's a legal requirement in some jurisdictions to protect privacy. A sad indictment of modern society, but understandable when you see this sort of thing
I seriously suspect that's indeed the case.
While there might not be an official laws in place just yet, the telco regulators are (at least in here, Malaysia) the one that make requests for certain market specific features.
I bought my S2 and first S3 in Monaco. Turning sound to Vibrate, didn't disabled the shutter. But then I bought second S3, Note 2 and S4 in Malaysia, where internet and telco laws are not keeping up with rest of the world (yet), and the Vibrate works like charm in disabling the shutter sound. Still does, on my brand new S4 LTE
I remember few years ago the trend for "up-skirt" photos, lead many phone manufactures to permanently removing shutter sound toggle, out of mere concern for the ladies.
And perhaps that's exactly the reason why firmware upgrade roll-outs, can be months apart between countries. There could really be, lots of OS flavors, based on location and telco specs. I can hardly imagine any other reason for such feature inconsistency.