Peter, it seems drum in disc handbrake operation worked well over many years, though perhaps now old hat.
Electrical handbrakes depend upon rather a lot of technology involved in their operation, requiring connection to a computer to carry out replacement of rear brake pads, a task which used to be relatively simple.
Found this vid which provides a general introduction to the electric hand brake system.
https://www.youtube.com/watch?v=dJLWXTEvkzQ
