Map apps let you look at any city in the world without needing all of that data inside the core app, and if you have enough data to use the Uber app wouldn't you almost certainly also be fine to have it download in the background the required info (coordinates of where pickup is or isn't allowed, specific instructions message to display, etc.) the same as it receives information about local pricing, location of available cars nearby and so on?
You need to think about the larger picture.
A quick summary like "extra fee for airport pickup: X, pickup location restricted to: Y, etc." should be pretty comparable.
Thinking of my experience with Uber at airports, it's generally stuff like "pickups from this terminal are only available at the west exit" (show on map - so needs coordinates and message text), or "There is a £10 airport pickup fee for all private hire vehicles here which will be added to your bill", or whatever along those lines.
But perhaps your point still stands even if it's KBs rather than MBs.
And for the specific UX, sure but isn't that just a single feature for airports in general, and the app can pull the up to date airlines/terminals data for the specific airport when needed?
As long as the airport rules can be stored as data, not code, then iOS would be fine with pulling them.. but at that point you have a data blob saying effectively "in country X, you can use payment Y", and you still need code that knows "payment Y means enable this section of the app and use this library"... and you can't download that library at runtime on iOS.
So my guess is that the code implementing regional rules have to be bundled with the app due to apple's restrictions, and the associated data that could be dynamically downloaded is to small to not just bundle it too.