Most guitars will be joined down the center.
I don't think the line in the mahogany S is the joint line. Mahogany can have distinct lines in it where it seems to change grain. Or the reflectiveness of the grain is different so in the right light it looks like a separation.
The mahogany JS700 with soapbars was Korean, but Joe is holding a Japanese one in one of the catalogs. (can't remember which) But the difference is stunning. The Korean looks dull and lifeless, while Joes sparkles in the light. His actually looks like several pieces about 1" wide glued together, because of the way the mahogany is. Mahogany also hides joints very well, and that could be why the grain path looks more like a joint than the real joint.