I have an 80 miles commute and 75 miles of that is on the freeway. Because my commute starts early at 5AM I rarely touch the brakes. Is this why my tires don't wear out much? I think with current wear rate I might have another 30K miles.
What tire pressures do you use? Others have suggested here previously that it's the tight turns that eat tires, and maybe not many of those in your routes either. I suggest that you (and everbody else!) change tires before the wear bars show. Those are 1.6 mm and wet traction deteriorates rapidly below about 3.5 mm. Nag nag nag.
I couldn't keep my Prius on the road during heavy rain at 15,000 miles on my Integrities; be very careful at 44,000 miles.