Drum brakes are one of the many things that contribute towards EVs becoming lighter than equivalent ICE cars over time, as they weigh less than disc brakes (about 25% lighter, 10lbs maybe, and unsprung weight too).

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.