Hornets are after the honey. As soon as there is not enough bees at the entrance, they get in.
The picture are from bee hives 2 km away from ours, last year, they lost 95% of their hives. 0% lost at the moment. So yeah, it looks bad but it works.
As soon as we will not have more than 1 hornet waiting in front of your hives, we will get them out.