Ford Fusion Brakes Defective

I like my 2008, Ford Fusion, except the rear disc brakes are defective. At 50,000 miles, I've already had the brakes wearout twice; get scored and last time--stick on one side. I'm told by my mechanic it is because of a poor design that incorporates the parking brake into the rear brake system. While there are other complaints on the WWW of this, Ford has merely noted my complaint and reacted to it by doing nothing.