Because the fact of the matter is that very few people who carry want other people to know they're carrying. That, and the fact that decades of concealed carry only has kind of made people more comfortable with concealed carry overall than would otherwise be had we had legal open carry for a few decades. North Carolina is an open carry state, and has been for a good, long time. But you just don't see that many people open carrying in NC. Yes, I've seen a few, and actually know a few of them. But it's not hugely prevalent. According to one website I looked at when I googled "SC concealed carry permits, number of", there are 308,406 active concealed carry permits in the state. There are 5,259,222 SC residents as of this posting. That means about 1 out of every 17 people on average have a CWP. Out of those, many will not be carrying routinely, most will carry concealed when they do, and a small fraction will carry openly. Those demographics will vary from region to region for a variety of reasons. If you assume one out of every 100 with a CWP open carry, that means about 1 out of every 1,705 people on average will carry openly.