That would be the fault of the tire manufacturer, not the retailer.
It could also be your fault for buying tires with a low tread wear rating. I never buy tires that are rated less than 320. Tried some that were rated 240 one time, good sticky tires, but I wore them out completely in 6 months. I like mine to last at least a year, preferably longer, but a year at the very least.
The higher the tread wear rating the longer they last. So you probably want something rated 500 or above, which is about a 60k mile tire.
The Cooper Lifeliners that are on my car have gone about 5000 miles with me behind the wheel, burning rubber and squealing tires around corners almost daily, they still look the same as the day I got the car. They're hard as rocks. They don't hold the road for crap in the rain, but they definitely last a long time.