I've never worked in fulfillment or shipping but it's possible that Apple's supplier took orders to direct fulfill orders to AT&T, Verizon, best Buy and others before apple really solidified how many orders to expect so they promises 10,000 units to Verizon on 11/31 and until VZW gets all of those 10K, Apple's supplies are restricted.
Apple also tends to beat their own estimates on Apple.com. Best Buy has even shown that they are saying not in stock but a few early orders have shipped for those customers.
I agree though, logically, the people who ordered on Apple.com should receive theirs first and no one else should even have them available.
Someone ordered AirPods on Apple.com on 12/26 ands to wait until mid-February. A VZW Customer gets them overnight ordering January 8th.