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.

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.

Usually the websites and apps you use, but not what specific page you visit and it’s content.

If you for example visit https://en.wikipedia.org/wiki/Labor_unions_in_the_United_States they could see that you visited https://en.wikipedia.org/ but nothing more.

This is assuming that the website is encrypted (it starts with https://, not http://), which nowadays luckily most websites are. Otherwise they can see the specific page, it’s content and most likely also all information you input on that page.

Every Rubik’s Cube, no matter how scrambled, can be solved in at most 20 rotations.

They blocked access in the back end, but didn’t adjust the frontend to deal with this situation.

If you try to access twitter while not logged in the frontend requests tweets from the backend, gets an error response and therefore tries again around 10 times per second.