> 5% is the worst, where a photographer will have a open license like CC BY-NC

Doesn't even have to be -NC. Creative Commons licenses require reusers to provide comprehensive[1] attribution when they reuse images. Some older versions of the license, like 2.0, also terminated immediately and permanently upon any breach of the license; copyright trolls have abused this to sue reusers who forgot to include some part of the required attribution. CC 4.0 provides the reuser a 30-day grace period to cure a violation.

[1]: "the name of the creator and attribution parties, a copyright notice, a license notice, a disclaimer notice, and a link to the material", as well as the title of the work prior to 4.0 -- https://creativecommons.org/licenses/by/4.0/deed.en#ref-appr...