Since no-one else in the comments seems to have pointed this out, I'm pretty sure these are all examples from real apps, which is how they're deciding which is correct.
It's not so much about choosing the "better" design (although in most of these cases one of them is objectively better), but choosing the design used in the real app.
There's one where the A option is an input with sharp corners, and the B option is the same input but with rounded corners. Which one of these is 'correct'? And why is it a 'best practice'?
It's not so much about choosing the "better" design (although in most of these cases one of them is objectively better), but choosing the design used in the real app.