This is because it is actually grounded.
Esd anti static flooring.
Both esd and anti static flooring prevent the build up of static electricity as people walk across the floor.
Other common names are anti static flooring static flooring conductive tile static resistant flooring non static flooring and grounded floors.
We loosely define those surfaces as esd flooring.
Esd flooring gives a much higher level of protection than anti static matting.
Anti static floors have a coating or chemical additive that dissipates static across its surface so you never build up enough charge to get a shock.
A static free environment is created by eliminating normal static generating surfaces like carpet rubber and tile.
The tiles are then laid out on top of a conductive grid.
Ecotile esd tiles for example have millions of small stainless steel fibres running all the way through them.