There are more than 1 kind of
page when talking about Ebooks (and web pages)
There is the (Meta-)
Physical page, which is all between <body and </body> (basically, the (section) file
and there is the Logical Screen page.
This last one is controlled by the render engine and what you see is dependent on a number of factors, Screen size, font size and Style commands like page-break-....
Paging here, is by screen (like clicking in the open area of a the scroll bars)