Europe is nearly 50 different jurisdictions, spanning multiple very different legal traditions.
But it is mostly not very murky. Moral rights and commercial rights are distinct in a wide range of jurisdictions. You can generally waive commercial rights, and that is for the most part sufficient for things to e.g. be "functionally" public domain in the ways most people care about.
What moral rights prevent is generally speaking usually things like for someone else to take your work and simply put their name on it, or keeping your name on it but making changes that might do harm to the creator in various ways.
There are nuances between jurisdictions, but it's generally not more difficult than being respectful of the effects (positive or negative) of attribution and integrity of a work.
I don't really disagree. Open source is generally recognized among European states and, from a practical perspective, permissive licenses are mostly indistinguishable from public domain other than preserving notice of the original authorship in some form. A permissive license does allow you to make pretty much any changes you want and sell it or use it in another product (or not).