Some anecdotes from Netflix: https://www.reddit.com/r/MachineLearning/comments/6xiwr4/d_w... (Scroll down for my comments. Ignore namp243 comments - see below).
Another example is the "Netflix prize team" at Verizon/Yahoo. They refuse to share data with any other groups (they are afraid of being discovered), leaving other groups literally nothing to do.
In my opinion Youtube recommendations are improving. They are still pretty bad but they are trying interesting approaches.