Toe and camber both cause smooth edge wear. Camber will create a feather edge on each rib. Think of a paper cup laying on its side. As it rolls one side is turning faster than the other. Toe is just dragging the rubber sideways, like an eraser. Balance is hopping up and down in the same spot(s). Loose parts and shocks are hopping and wobbling randomly.
180 degree separation would account for first order imbalance, what about second and third order imbalance?
No amount of toe will create scallops, unless the wheel doesn't spin. Then you'll have one HUGE scallop.
(p.s. the leading edge is the one that will show wear.)