I think the problem is that customer service people don't have any specific knowledge of what is happening, and they give out 'information' which is either just generic, or they've heard from others. I've come across that a lot in telephone support - and it is a very common issue with call center type support where reps can actually be handling calls relating to dozens of different services or products.
The 'what embargo' comment from Apple is a great example, because there IS an embargo placed by Apple on all pre-order stock in the delivery chain, that shippers can't make deliveries until the date Apple specify, at the earliest. For the iMac, that was May 21 of course. Hundreds or even thousands of boxes wait for delivery in staging points, waiting for the 'release date'. Any Apple rep that doesn't know this is very poorly informed, and likewise, one who denies it happens is likely just assuming we're not supposed to know how it actually works.
And my experience with FedEx, UPS, USPS, and DHL is that when their anticipated/projected delivery date passes and the item is not scanned as delivered and thus off their books, tracking will show 'pending', because at that point their systems are waiting for intervention - someone to actually input something.
