When the gecko is a reptile that climbs on smooth surfaces such as glass using van see waals force to adhere to the surface. how is this method of adhesion more advantageous that covalent interactions?

In physical chemistry, the van der Waals forces is the sum of the attractive or repulsive forces between molecules other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules. Van der Waals forces are relatively weak compared to normal chemical bonds, but play a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics.