Drum brakes have been around for a century, afaik they're more robust than discs but "lower performance". These look like a variation on a pretty standard design at first scan.
Maybe dust in the drum isn’t a problem? Or maybe it’s designed so the dust accumulates somewhere other than on the friction surface inside the drum?
As the link states, they also increase efficiency, and that allows for smaller batteries, less weight. They're also looking into lighter weight aluminium disc brakes because EVs use them less, and it prevents issues with low usage disc brakes rusting.
This is because of regenerative braking not using the brake pads, using the motor instead.