In point of fact, in putting The Balearics on the risk list, Germans returning are required to take a Covid test, and those returning who are positive will have to quarantine until they receive a negative test to the best of my knowledge (the DW piece infers this too). Nothing wrong with that; in point of fact it's what the UK should have been / should be doing for months now, but isn't. The Italians are doing similar.
Of course the whole airport testing thing falls flat on it's face when positive results aren't being given to people, as has been the case in Bavaria.