Are "Stock Photo" websites using pictures they don't own?

Every once in a while, I go searching for pictures I'm interested in, and eventually I come across a site called “Alamy”. I've often suspected that these people sell pictures they have absolutely no right to. Fair disclosure: I hate the website because they ruin the pictures with their “watermark” and because they flood search engines, making it hard to find alternative pics. Well, today, I found out I was right.

This is the alamy picture I stumbled upon:

They charge $19.99 for this photo for “personal use”, $49.99 to use it on a website.
I had already seen it here:

And it's listed as public domain*, and available for download on logging in.

Here's another picture I saw on Alamy

after first seeing it in the public domain*.

* The DVIDShub says in part, “In general, DoD VI that are works of authorship prepared by U.S. Government employees as part of their official duties are not eligible for copyright protection in the United States...”

It also states, “No Representations or Warranties. DoD makes no representations or warranties of any kind regarding the suitability of using DoD VI for non-DoD purposes. Use of DoD VI is at the user's sole risk.”

And “Publicity and Privacy Rights. VI postings by the DoD do not waive any publicity or privacy rights of any individuals portrayed. For example, to display a photo of the Commandant of the Marine Corps on the cover of a cereal box would likely violate his rights, not to mention infringe USMC trademarks.”

And now I'm sorely tempted to report the website, but I don't know who to report them to.