However given that so much of the airline industry relies on systems that were developed decades ago, perhaps I shouldn't be surprised.
Are you implying that old code is inherently inferior to modern code?
I would agree that modern languages make it easier for devs, but they also make it easier for devs to make mistakes too.
Decades-old code written (and tested) using waterfall project management methodology for the FAA may be an exemplary case of build it right the first time.
That the expected use case(s) [normal behavior] works smoothly as frequently as it does I think deserves some kudos.
The new behavior of customers/users (incl. airlines) to book multiple daily trips to the same destination with the same plane or to change seat assignments in near-real-time, etc. being driven through decades-old code (that maybe didn't anticipate 'modern' craziness) with as few mistakes as we see is also pretty amazing.
I'm not trying to be an apologist for crufty old code. However, in some cases old code survives as long as it does because it works so well there's no reason to risk system stability by replacing it with the flavor of the month.
I'm sure you wouldn't make age-ist remarks about coworkers, just shedding light on the attitude towards "old code" 🙂