Copyright isn't a US thing - its an international thing. One doesn't have to register their copyright in every country to publish a picture (for that matter, they don't even need to register the copyright to have it be protected).

I didn't even go down that road. There's nothing compelling a Dutch company to comply with the DMCA. The context of "illegal" that was quoted a few comments up isn't "DMCA", it's "illegal". Like, against Dutch law. Child phonography might be a good example.

On that matter though, here's what copyright.gov has to say:

"There is no such thing as an “international copyright” that will automatically protect an author’s writings throughout the world. Protection against unauthorized use in a particular country depends on the national laws of that country."

https://www.copyright.gov/circs/circ38a.pdf

There is such a thing, actually. Not explicitly, but international copyright law has been largely harmonized through the Berne Convention. With 179 signatories its a pretty universal 'floor' for copyright protections. The only big abstention was the USSR and they aren't around anymore.

https://en.wikipedia.org/wiki/Berne_Convention

The pdf I linked covers that in pretty good depth.