@juliemoynat true. Sadly
Color is actually not easy and basic, and some attempts to make it "easy" have ended up making it "wrong", leading to misinformation and misunderstanding.
Importantly, and this doesn't get talked about enough, what is best for one individual can be harmful to readability for another.
Also, if talking about contrast, it is the spatial characteristics meaning size, weight, thickness, that are most important for readability contrast and actual accessibility.