I see it more when a track has long sweepers and the inside tire is unloaded and with a lot of ackermann being dragged thru by the front spool. If i see this happenning i try to swap my fronts (left-right) every run.
on the outside tire if your car is understeering a little I see it because at max steering angle the inside part of the tire actually rolls over the inside sidewall meaning you have a more solid thing under the tire surface than just the insert causing more wear in that particular spot.