[KingJulian]

I would think so too. Any parking brake has to be a fail-safe type brake which has to function in the absence of electricity. Hence, as you mentioned, purely mechanical.

[Sohcahtoa82]

They need to be able to remain applied without power, but the application can require power.

In my Tesla, I push a button and I can hear an electric motor engaging the brake.

[kwhitefoot]

It only has to remain engaged, engaging it in cars with push button parking brakes requires electricity to drive a small electric motor at each wheel.