This table was made with a thickened top which means that only the edges are as thick as the top looks.  Stonemasons do the same thing when creating kitchen bench tops from 20mm stone material.  In this case the timber started off being around 32mm thick before it was glued back under itself to create this beautiful very thick look. 
Timber is usually not available in such thick sizes unless it's recycled timber which may have been used for structural purposes in a building.