Once you go beyond immigration and security, most airports have poor quality food options, with poor service, at expensive prices.
This is because the airport is a transient place. The majority of travellers are there briefly and infrequently. And they’re a captive audience; they can’t leave the airport to get better food elsewhere.
It’s an ecosystem where no one has to be excellent to survive, and that has the consequence of bringing the overall quality down to an unusually low level.
At this point, it makes sense why airports bring in the big fast food chains. It’s likely no airport executive got fired for signing a contract with McDonald’s.
I don’t have a solution because I don’t think there is one. Any ambitious restauranteur would likely make better margins elsewhere, so it looks like we’re stuck with mediocre airport food for a while yet.