well there are 3 ways that wear can occur on the inner edge of the tire. but more info would help, like did they put it on the alignment rack and measure the angles or did they just look at it and say yep its camber, also if you could get a pic or two from different angles that would help.
A) too much toe in/out. this will generally cause a smooth appearance on either the inner or outer edge of the tire depending on toe in or out.
B) too much camber. this can give you a feathered or chopped look to the inner/outer edge depending on + or - camber
C)under inflation but that is on both the inner and outer edges so i wont bother with that one.
A is an easy fix theres a write up on how to align your jeep in ur driveway its under the tech section
B could be a couple of things, worn ball joints or a bent axle tube. but how he could bend the axle tube down to cause that wear is beyond my comprehension.
My bet is on too much toe out, in that case i would check the steering system for loose and worn parts. the shop should have checked for loose worn parts before even attempting an alignment as worn parts wont give you a true reading.
someone can correct me if i am wrong or am forgetting something.