People fail to realize that Apple is sending out more phones than UPS can handle at once. They're only humans with a limited amount of time at their disposal to deliver. They try to get out as many as they can but they can't get all of them in one day. And I speak as fellow delivery driver, no not UPS, from experience in saying when more delivery requests come in than all available staffed drivers can handle, delays will crop up.
Gosh, I wish my company got a pass like this when we fail to meet our one and only obligation to the business world.