I know. But once you get above a certain point (10,000 miles per year, I think) the rates don't change. USAA is more interested in how the vehicle is used than in how much it is used. Someone who takes a bus to work most days but puts 12,000 miles per year on the vehicle pays a lot less than someone who drives five miles each way to work and puts only 5,000 miles on the car.
I have no knowledge of how they charge for commuting to/from work. Until recently I had one vehicle @ 20,000 miles per year used in my work and a second vehicle @ 3000 miles per year for pleasure. Of course there was a difference, especially with the second car discount.
On the other hand, where you drive is significant. The difference in rates for Dallas County, TX and a west Texas county are sizable. And the difference between Texas, where they sell County Mutual policies thanks to the legislature, and Arkansas, where it is a casulty policy, is also significant.