Because in most of the cases you are transiting and no one cares. If you would have said to any of those border guards that you are coming to stay in any of tho

Because in most of the cases you are transiting and no one cares. If you would have said to any of those border guards that you are coming to stay in any of those countries, they would have cared and asked for more things. Saying this as I travelled recently from Germany through 4 countries. In the destination country they asked for test, proof of sickness or vaccine proof.