People learning songs by playing by ear and even proforming them is one thing.
Selling sheetmusic that you may ‘claim’ to have done the by ear method to learn is another.
And yes, making a cookbook based on a restraunts recipe should and is illgal if they have taken the steps to protect the recipe.
I thought better of my post after I had taken more time to think on it. I was thinking that this website in question just had the information on it, not that they were selling books... I’ve never heard of the website before this thread.