Static pages pagination /page/2/

On every WP site you can add this slug to URL /page/2/ and you will get the content of the original page. Examples:

https://wordpress.org/page/2/
https://woocommerce.com/page/2/

This occurs not only for the homepages but also for the other pages. Why WordPress generates this pagination if those pages are not blog index pages? Where I can read more about this for better understanding?

Why it doesn’t happen like this by default (when the URL doesn’t exist display 404):
https://www.whitehouse.gov/page/2/