They use a tiny little brake drum inside the rear rotor, they're almost useless on any hill.
Apart from the size of the drums and shoes versus the mass of the vehicle, I think the main problem with the design is that there's insufficient mechanical advantage in the shoe lever system so the shoes can't be held hard enough against the drums, no matter how tight the cable is drawn from the driver's end.
It beat me how such a poor design could be carried forward from model to model until I noticed on reading various forums that many Americans simply don't use the parking brake. In fact, you'll read about Corvettes where the shoe mechanism has rusted tight in the brake-off position from lack of use.
I guess if they're mostly automatic transmissions driven on fairly flat roads, then the Park lock on the transmission does the job for them.
On the other hand, if you drive a heavy Vette with a manual transmission, the p#iss poor handbrake is not much fun when you're stopped at lights on a steep uphill climb.
I always leave a manual transmission car in gear when parked. And if I'm parking the Vette on a hill I'll face the wheels into the kerb for added safety.
