Specs
If the SVTF is set dead on spec, it will not wear tires abnormally. The problem is in your alignment man's machine and his attitude towards the adjustments.
Instead of thinking that adjusting the suspension is THE most critical thing to make the car handle properly, he is looking at it as a way to make dollars. The more the better. The faster the better. And, many alignment machines have the +/- tolerances WAY wider than the chart below. It is to make more money faster.
So long as the numbers come up green (within the tolerance span), I will bet that he isn't touching it. As you can see, the car can be pretty toed out and still technically be in tolerance. You are wasting your money getting it aligned so often too, unless you hit something hard enough to throw the steering wheel off center. Otherwise, I rotate the tires every 5000 miles and check alignment when getting a fresh set of rubber.
You might ask to watch him next time and have him print out the actual specs he has the car set to. This might encourage him to do it right for a change.
Oh, and notice that the specs are in fractions of degrees...not inches. Makes a big difference on these cars as they are a little sensitive to adjustments.