First off, I realize [and pointed out] the 'principle' of the discussion. A given.
Back to the real world: NO vendor is likely going to ask their staff to search for the freshest dates among dozens of tires in several warehouses, just to accomodate an irrelevant premise. The tires are racked, First In, First Out, in every tire warehouse. Larger racks are fully automated.
Nit-picking to get fresh for fresh sake? If it was bread, or lettuce, OK! What if 1 newer tire is in Reno, and 1 in Delaware....who would pay an extra $30 in shipping to receive a 4-6 month newer tire? NOBODY! Why waste the labor-time looking? It is a baseless argument according to the experts.
I just had a large carport built....6x6 posts. 12 of em. On principle, I know that if the wood was newer it would last longer, but DAMN: The posts they delivered were almost 3 years old. In principle, I got shorted. I wanted NEW wood. In practice, it does not matter.
Real World # 2: No tire seller is likley to even KNOW the various studies that show 2% aging per YEAR of proper storage. Luke just posted another that says "no measurable loss" after 3-4 years! So, would you really ask for a 2%-4% discount ? If manufacturers and vendors allowed that, some would hunt for 3-year old tires, knowing it DOES NOT MATTER, in hopes of saving 6% !