When you order a Boeing it's circa 50 mil for a basic aircraft, an Airbus will be a lot higher but will come fully equipped to meet EASA regulations.
So you can announce a bigger future order of Boeings and they look like a really good deal. But when it comes to equipping them you then have to pay through the nose for Stall Warners, RNAV capability, ACARs, Fail operational autopilot systems etc. So the aircraft end up costing 2 billion + 1 billion for add ons. But only the 2 billion goes down on paper.
Utter madness by the bean counters to not expand the A320 family fleet, it would have been a smaller deal but could have avoided huge costs in re-training and changing ops. But then I guess it made a really good
PR stunt. Just an absolute pain for those staff a few years down the line who have to deal with it.