Just for comparison, I'm flying to Spain at the beginning of next week and I had to start the process of preparing for that, 2 days ago.
I need a negative PCR with a special identity confirmation on the test result, which meant going to a specific test center that scanned my passport and linked my test to that.
I need to fill in a form and have that, plus my test result, ready for when I check in at the airport. Check in is compulsory for everyone because here (Germany) you must now put all your luggage in the hold - small hand-luggage suitcases included, so security control can run smoothly, and less people will get up during the flight to access their baggage. Small rucksack and that's it.
Said form will create a QR code that I will scan before exiting the airport after landing in Spain. I will also have my temperature taken, and the medical staff at the airport do a quick visual test to check you're not ill.
Similar procedure coming back to Germany, except that you must quarantine for 5 days first before you can get a test and be released from isolation. Oh, and they check you're in the house whilst you're doing your isolation. They have people who actually check those forms and call/email you regularly.
That's how these countries aren't getting many cases from overseas, because they have procedures in place to minimise imported cases.