Same in DK, and my comment was meant to underline that. If you see a drone and no operator is around, then something is definitely wrong.
I mean, years ago, I had a DJI Phantom 2 Vision+ drift away, on account of my own inexperience and stupidity. This was right when it had just come out, and way before drone licenses and laws forbidding drone flights in populated areas. So no laws were broken; and it was done with no malicious intent… But these days?
Not even the DK police, who have some very well-trained drone operators, can fly their drones out of sight.
Seeing a drone with no operator once? Something might have gone wrong, let’s not judge too harshly, but seeing a drone with no operator regularly? On your property? If you have a hunting permit, a shotgun, and a clear shot, then it might be a good time to practice your anti air skills.