It is very disappointing to go to a store and find that they don't have the merchandise you want to buy, but it costs money to stock stores. There are 1,800 AT&T stores and 162 Apple stores. If we assume a 50% markup on the iPhone, it cost over a half million dollars just to put one iPhone in each store. If each store had an average of 20 iPhones, they had to front over $10 million on speculation that the merchandise would move. That's a lot of money.
Apple and AT&T are businesses, not philanthropic charities, so they have to estimate the demand, figure how much money they can spend on a product launch, the risk of demand not being high enough on the first day, the willingness of the bank to accept their sales projections, the capacity of the manufacturers, the reality of overseas shipping, the capacity of the shipping companies to deliver the merchandise, the capacity of the stores to stock the merchandise, and how many boxes the employees could receive and unpack in the available time.
There was a company that had unprecendented demand for their first computer. They rushed it to market, and as a result, the first run had a lot of quality problems. That earned the computer the nickname "Trash 80" and they never overcame that initial impression.
Apple would rather face a small shortage than destroy its corporate image and lose its customers. So I think they did a good job of balancing all the factors.
Now that they have sold all those iPhones, they have the money for the next batch.
