Before youtube disabled recommendation for people with watch history turned off, having watch history turned off made it so your recommendations were only based on channels you are subscribed to and possibly videos you’ve liked, commented on, …
There are some categories where I only ever search for the category, then watch a video, but never subscribe to any channel. Those videos were never recommended to me. Meanwhile on my girlfriends pc with watch history turned on, as soon as I watch a single video from a channel she’s not subscribed to similar videos appear all over the front page.
I don’t think google fear Apple having to offer a choice to users. They fear Apple defaulting to Bing or something else.
While most people might choose google when presented with a choice, possibly more people are just going to keep the default settings when not presented with a choice.