Because airports charge a lot of money to the businesses that are there [0]. So the businesses have to appeal to the widest selection of travellers, so you get

Because airports charge a lot of money to the businesses that are there [0]. So the businesses have to appeal to the widest selection of travellers, so you get the most well known international brands and most general, safe, and average food. Craft beer is still mostly a speciality, and a lot of it is an acquired taste [1], so it cannot appeal to the majority of people. [0] For example there was an article some time ago detailing plans RyanAir had for offering free flights. They (and the airports I presume) would make money from the things passengers buy at the airports. [1] Bitter IPA, Sour beers, smoked beers, etc. Whenever we go out drinking craft beers, I always ask for a sample before I buy because there is always something that I don't like the taste of. I made the mistake before of ordering pints of beer and not being able to take more than a sip.