Netflix. Amazing and consistent user interface on every platform
But at the time I’d list it as an example of user hostile UI. It had lots of unpredictability (few fixed UI elements). Also: autoplay and a search that never says if an item is not there but tries to offer alternatives.
I disliked it so much that whenever I wanted to watch something on netflix, I’d first check whether they actually have it and I used a different tool for that.
Thus they have to try to make the most out of recommendations, and try to maintain a bit of an illusion that their current catalogue is bigger than it actually is.