Quite right. And on the flip side, who would have guessed that haggling down the price of a super cheap at-cost AZ dose and playing hardball on liability when everyone else was bending over backwards would result in delays and supply problems for the EU...
Who would have thought ordering twice as many doses as needed wouldn't be enough for some? And who would have thought that ordering more, and above manufacturing capacity, would reduce availability?
Overestimating doses required allows you some room for manoeuvre. Plans can change, like when the Sanofi/Merck/Pasteur vaccine tuned out to be a dud and was abandoned within the EU.
Manufacturing capacity at the continental AZ facilities have been hit by teething issues. There were also teething issues at AZ's UK facilities, but the impact was less because the order was placed three months earlier in the UK.