If the tire is worn evenly across, but worn more than the others, it is most likely due to spinning the tire. Weather that is because you race around and take off like a bat out of hell, or just simply from poor weather conditions, I have no idea. Another big issue that will add to this is lack of rotating the tires. While those are the 2 most common reasons for that, it is not impossible to have a defective tire. I have had tires with improper rubber compounds wear like that on a vehicle. (worked in tire store for 12 years)
I had a customer that brought their car to me for maintenance on the tires and with proper rotations and alignment one tire did wear faster than the others, and I mean a lot faster.