Dell Techs do not appear to properly ground

Just had a laptop mb replacement done by a Dell Tech.

He placed an anti-static mat on the table, with a wrist band attached; however, there was no direct connection to ground. I do not really understand how this can work, given the laptop case is insulated. In this case, I would think, both the tech and the anti-static mat could have a high static potential.

It is also the case that all Dell videos regarding performing hardware upgrades makes it quite clear that a ground connection must be made to the user working on the machine.