One of my photos are used without permission by an american company. I have one question to ask. What is the normal amount you would ask for use of a photo without any agreement in America.
What someone else would do in another situation is not relevant... the real question is, what would you have charged them to use such a photo if they asked?
I mean, if Apple uses my photo of an iPhone on their website, that's a big dollar problem. If Esmerelda's Tarot Card & Palm Reading uses a beach photo on the wall because it's soothing, maybe I just ask for the cost of the print.
I also wonder about photos displayed on Google+ where Susie has chosen to share her photos. Maintaining control of one's work is increasingly difficult in the world of social media. I wanted to post a comment on a piece of music I heard on Youtube and suddenly found myself a member of Google+. Fortunately, I was able without too much difficulty to extract myself from that quagmire. I know it works for some folks but simply holds no interest for me, especially since being a member of Google + changes completely how photos I have uploaded on Picasa are handled.
I mean, if Apple uses my photo of an iPhone on their website, that's a big dollar problem.
Maybe that's not the best example, but it does raise another concern. The iPhone design is copyrighted, trademarked, and Apple"s intellectual property. You may photograph their design for editorial use, but that's it. Your copyright doesn't supersede their copyright. Barring a few exceptions, photographing works of art including things like buildings, paintings, statues, most products, etc. for advertising use is not recommended unless you get permission. If you fail to get their permission it would most likely be the original creator suing you, not the other way around. It's unlikely that Apple, to name just one company, would use non-assigned photos on their website.
OP: As for the "one question", any answer would be as vague as your question. It is in your best interest not to start an international copyright infringement lawsuit unless you have the money and time to proceed. It's a complicated process with no guarantee of a positive outcome. I think that the infringers know that, sorry to say.
Then apply that to the fact that OP lives in Denmark and is filing suit in the US. The international laws are favorable between the two countries, but as the ASMP explains it is sometimes not worth it just filing within this country, and a lot more complicated outside of it.
I know of a photographer who sued a company for re-publishing his many photos in his book without an updated agreement. The company, knowing it was in a losing battle, sent him a check for $35,000.
It all depends. There is no established figure. I would bill them first and see what happens.