Since they were not given exclusive rights, how could they know that whoever used the picture was infringing their rights and had to pay them a license fee? They didn't.

The whole example was about having exclusive rights so anyone that had the image must be infringing. That presumption is gone once the image is in the public domain.

The problem isn't that Getty is trying to license an image, the problem is Getty is contacting people already using a public domain image and trying to get them to pay them money to use it.

What "license" was sub-licensed?

You can't have a sublicense for something in which no licensing rights inhere to begin with. I think you understand this very well and are choosing to pretend otherwise.

That is not how grammar works... . The point is about exclusive sublicensing. Of course, they are allowed to sublicense it, nobody ever questioned that, but that has nothing to do with the discussion.