The sand lie's make sense to me at Kiawah. Maybe Tarheels can verify this, I think WGT did their homework here.
If you are away from the edge of a fairway bunker, you get hard sand. This makes sense as the wind blows it around all the time, dispersing it. It you are close to the wall of the fairway bunker, you are in deep $#*^. The wind blows the sand around and it piles up there.
All of the green side bunkers are fairly shielded from the wind, when sand blowing around gets in there, it stays in there, so it is softer sand for sure. I have never, that I can remember, been in a green side bunker with better than a 30% lie.
I do agree the sand on BPB is easier to contend with. It hasn't been worked over by that little thing called the Atlantic Ocean for millennia.
On BPB, 90% of my greenside bunker shots are Pitch. Can't really do that on the island.