Writing copyright guidelines for a project such as Wikitree is a very complex and difficult process. For years, I served as a copyright adviser to the Project Gutenberg Literary Archive Foundation and drafted such guidelines for their project which mostly involved old published books. That simplified the task of writing guidelines a great deal, but by its very nature, genealogy sources can't be simplified by such a limitation.
The rules are complex, especially for a project involving the Internet. Copyright laws differ from country to country and the law of many countries has not addressed internet issues. For different questions, the laws of different countries may be involved, and there are very few experts knowledgeable about the copyright laws of multiple countries.
Second, copyright law changes over time, so the guidelines need to change and be kept up to date.
Third, it is very time consuming.
Most importantly, for a high visibility project like Project Gutenberg or Wikitree, copyright issues can be very risky. I can attest that various copyright holders from various countries can and will take action based on their copyright claims causing serious headaches for the project even if the project stays within the boundaries of the law of the country from which it operates.
Wikitree, by its collaborative nature, invites participation from genealogists in a lot of different countries. So it can't really confine its operations to the laws of a single country and post guidelines based on the copyright law of that one country. That one fact makes both the creation of guidelines or help pages infinitely more complex and the risks infinitely greater.
Because of this complex situation, genealogists have to rely on general information posted by lawyers in their own countries like
https://www.legalgenealogist.com/ on U.S. law and abide by the policies of the various sites they use.
I once was an expert on U.S. law on these issues, but after leaving academia and switching legal specialties about 17 years ago, I haven't kept up with all the changes. I can say, however, that the information I found on
https://www.legalgenealogist.com/ is in keeping with my knowledge of the subject when I stopped specializing in copyright law and it relies on citations to experts in the area that I know have kept up with the changes.
As a genealogist and researcher, I am frustrated by the limits this imposes on sharing sources and especially photos, but I've accepted its just one of those things in life we can't change and have to live with.
Mary Jensen