At least in the US the problem is that you can’t afford to shut down existing airports and so a lot of the remodeling ends up being hodgepodge and convoluted ex

At least in the US the problem is that you can’t afford to shut down existing airports and so a lot of the remodeling ends up being hodgepodge and convoluted extensions and fitting whatever goes into a nook or cranny. The last major airport to be built in the US was DEN in 1995.