I don’t think there’s “no” adjustment, just very limited range which always is going to end up w/ neg camber.
My old housemate had a '04 G35 Coupe for a long time, and he had it DUMPED. It only had springs swapped, no other susp changes. He ended up w/ a pretty big amount of neg camber. Even still, he got about ~10k out of a set of tires.
My Z06 has -2.8 front camber with 0 toe and at about ~5k on the front tires they are easily half life. Across the middle to the outside of the tire they look practically new, the inner edge is pretty worn (obviously). The rear is -1.7 with .25" total toe-in. The backs have about the same mileage on them and actually look better than the fronts (after getting about 7k miles on a set of $1k back tires last time I’m taking it a bit easier on these ones, haha). My race tires wear perfectly even… but of course all that neg. camber is setup for racing, not street driving.
That thing must have a lot of toe in or out to be killing tires that quick. Something is wrong, and its a known issue w/ those cars. I’d go beat Infiniti up on this one.
-TJ