You don't, many modern cars have electronic parking brakes with small electric motors mounted on the rear calipers which push the brake pads against the discs when activated.
I am very glad you commented here as my initial skepticism of your claim lead me to do a spot of research that answered several unresolved questions I'd had about one of the most obnoxious features I've ever seen in a new car. My mother in law has a car with (apparently) electronic parking brake and I have loathed everything about it from the moment I first sat down in the car. This at least explains why an utterly unintuitive double toggle button replaced the "standard" mechanical lever on the center console and what notional benefits (hill holding) come with this system. I'd hate this a lot less if the manufacturer had included a tell-tale of some kind to visually indicate if/when the ECM thinks the P-brake is engaged.
If it's using brake pads, then it's still a partially mechanical suggestion. The comment at the top of the thread was suggesting doing away with brake pads entirely!
