People don't usually count reading an online piece of writing as equivalent to reading a book, even if the exact same content could also be in book form. Hence

People don't usually count reading an online piece of writing as equivalent to reading a book, even if the exact same content could also be in book form. Hence if you ask speakers of a language with a lot of available online reading material (English), you may systematically underestimate how much they read long-form content.