Heathrow is well oiled machine in many respect and handles more departures in their coach station per hour than Stansted does, despite Heathrow being 16 stands on the coach station, and Stansted being 33 stands (40 stands minus 7 for local bus). Bearing in mind too, that Heathrow there are also restrictions that mean tri axle coaches can't be positioned next to eachother so there is more considerations to juggle there.
So while not like for like, and while Stansteds way of working has some benefits (keeping departing and alighting pax more separate), but the pandering to NatEx because of NatExs inability to have a big enough depot for their buses is just a joke.
This feels like a National Express issue and between them and Stansted using this as a nonsense excuse for not permitting competition. "Sorry this airport can't handle any more buses because two of the operators are dumping buses because the 10 minute drive to the depot is too far for them, or have got themselves depots with not enough space". They all need to get a grip and move into the real world. If NatEx depot isn't big enough, that's a them problem. It's not for an airport coach station to pander to their needs and restrict access from other operators.
"out of the way" being....... the whole 10 minute journey! If Stansted are falling for this, they either have no backbone, or they are gullible. And even if they are keeping some buses on site, given the fact they only run half hourly, they quite clearly do not need 3 stands and I find it absurd that anyone is trying to justify that having 3 stands for a half hourly service, is perfectly ok and at capacity.
I'm sorry, but any argument that Stansted is full, is hyperbole. There is shed loads of capacity there if it was managed properly as a bus/coach station, not as a NatEx/Flibco dumping ground. Flixbus has proven in the likes of Leeds and Bristol that they can run a highly intensive service from even just a single drive on, reverse off bus stand.