Did anybody realise that the work needed to establish a new customs IT system was unlikely to be done in time, and what that would mean?

Was everyone already aware that UK airlines like easyJet would need to set up in the EU27 and Ryanair might move its planes to EU27 countries due to the UK leaving the Open Skies Agreement?

Well, some people knew, but they’re just experts, so have been largely ignored.

The death of expertise isn’t a UK phenomenon, of course. Trump supporters are notorious for ignoring facts (let alone experts who know something about those facts). But this has been a pervasive part of western culture for awhile now. It needs to change.