why did rotor on rear brakes burn up on inside only both side? no pad left on 2004 Chevrolet Avalanche 1500

only 13,000 miles on new rotor and brakes all around...why did it only wear on the inside rear both rear brakes

Likely crorosion has gotten into caliper slides. Calipers need to float in its bracket so pads can wear evenly. Botton line your truck sits too much thus that allows rust to build up and too much chemicals are used on the roads for ice. Drive it more...its a great truck.