Apple counts sales in customer hands, not sitting on retailer shelves.
They count both: sales they have delivered to online buyers or directly in their Apple stores, along with sales to retailers (whether sold to an end user or not).
Fact is, they're sold out everywhere. Seems more a supply chain issue than a problem of low demand.
The forum threads about availability indicate that major stores in large cities are sold out, but stores across the rest of the country generally have plenty.