Earlier quoted context omitted.
Well yes. But it is also a mistake that should have avoided and Apple are usually better than this. This suggest they have under estimated for one reason or another. My guess is that they were extra cautious in case of a flop just before new CEO was appointed.
Not really sure how else to unconfuse your logic here. If Apple's expectations were low where you say they underestimated, then it is exceeding their expectations. Whatever logic Apple used to decide that number doesn't matter. They expected sales to be X, but the demand is >X. I seriously doubt Apple planned this just get an extra news cycle like this. That's something a start up would do.
They have also not stored enough unit before launch. The wait is nearly 3 weeks. It is a good problem to have but also a problem that if they are targeting education they only have 2 months to ramp up production.