I can offer some anecdata. For some reason or another, Bing is better than Google for finding otherwise copyrighted work ( I was able to find Morty streams after new season came out ). My personal pet theory is that since Google was first to the game with majority market share, copyright holders and the like concentrated their effort on it. Needless to say, it is just one person's experience. I will admit that DDG still lacks in that area, but it has improved.