Whilst it would not be too difficult to reconfigure airports between "safe" and "not safe" countries (different terminals?) I can't see how, once Europe reopens its borders, you cannot treat the Schengen zone as a single entity. Does it make sense not to have to quarantine if arriving from France, but to have to do so if arriving from Belgium or the Netherlands? Is Basel airport in France? (Owing to long queues in Swiss security I went through the checkpoint to France on one occasion and sure enough the security queues were much shorter.) The airside is basically a common zone with exits to France & Switzerland, which are both in the Schengen zone. Prior to covid you could travel around the Geneva and Basel areas and cross borders without realising it, and if not the case yet it will hopefully soon be so. I'm sure that you could add plenty of other examples in the Schengen area..