And that picture is also *clearly* not a 6' wide table (it looks to be closer to 3' wide), indicating that it isn't actually a picture of the table being discussed. Or did you miss that?
The article said they're 4' wide, but yes a table does not look 18' long in one of those photos.
I was thinking about how you could possibly make a 18x4 tabletop from one piece, and it hit me that you could put a log on a giant lathe, and using either a 4' or 18' wide blade, peel a long thin piece in a continuous motion as you rotate, similar to peeling an apple round and round down to its core.