The weight of the aircraft does not impinge on the surface so only the weight of air above that point is acting on the surface.
The rotor downwash is not constrained by anything and so flows outwards - you can see that occur when you hover over grass.
The rotor imparts an acceleration to the air in order to create thrust to balance the aircraft weight - the air accelerates downwards because of the rotor and outwards because of the ground - still no requirement for a pressure increase below the rotor.