because the airport can’t be bothered to build a terminal big enough to satisfy demand.
Demand is fickle. Look at Auckland. Four A380's on the ground at once at the moment. Imagine the infrastructure costs to support that. Come March next year, there will be none (and Auckland apparently found out about that at the same time everyone else did). Who covers the costs of that infrastructure after that? Runway demand drives holding delays far more that gate space. Under the current (for the short term future anyway) terminal structure at the major east coast ports, gate access is Airline specific. so if you roll of the runway and your gate isn't ready, that's your companies fault. The airports operate to a slot system, but if 3 or 4 aircraft push at once (and that happens all the time), all but one of them are going to be sad. Who's to blame there? Ground infrastructure is a huge expense, and it takes time to build, and you can't just terminate the lease and give it back if things don't work out like you can with aircraft. You have to be damn sure the demand is there, and that it is long term and sustainable. If you had built heavily during the east coast FIFO boom, you would be very unhappy now.