There's a huge irony I have found in my over-traveling in recent years.
Airline people have experience of multiple airports, as do their crews and customers, this allows a balanced judgement. Airport managers don't travel nearly as much, (why would they?) or if they do, they're not paying attention.
Airports are, ironically, fundamentally local. They have a BASIC DfT framework they are obliged to work to, but they are free to add in tighter local controls, in the case of MAN, I have been told at least twice "This is the Manchester way, we do things better here." That's local thinking driven from local management, it causes a huge amount of frustration with people who have may have literally seen the same problem addressed in a much more efficient way at the airport they started their day at. It can be done well, look at how much better Gatwick is. Glasgow also has a huge new security hall, albeit one which drops you into shops......Edinburgh I am not convinced about alas.
MAG has done what BAA did at LHR in the 90s, they took their eye off the ball and allowed the infrastructure to become slowly unsuitable for purpose until one day, it breaks.