A couple of thoughts:
Tread depth: It is pretty common for tire manufacturers to make mistakes in their listing for tread depths. The molds measure one thing and the tires get stretched out and measure something smaller. Frequently the mold tread depth is just a bit over 10 1/2 32nds, so they call it 11, but when inflated the number drops below 10 1/2, so it rounds off to 10.
Tire age when purchased: Tires don't age much when properly stored. All the tire manufacturers have warehouses that are properly ventilated, so they stay cool and out of the sun. I haven't seen any tire distributors that aren't the same.
But tire retailers is a different story. The vast majority have good storage facilities, but every so often one will try to store tires out in the sun or in an old shipping container. The good news is that these are rare and can almost be discounted.
When I was working, the company used a 3 year limit for their own internal practices. They had a lot of data that supported the notion that 3 year old tires performed at the same level as brand new.
At 2 1/2 years, they would offer a discount to get them out of their hands - with the idea that the wholesaler/retailer would pass the savings on and the tires would be quickly sold.