Most readers I've encountered show their book contents as text, ie. as a continuous stream, instead of the "page view" you find in physical books or PDF. the "next page" button brings you not to "one page ahead" but instead to "one page worth of text ahead".
What would it take to have it display immutable pages with original (or fixed) page layout? Is it a matter of reader's brand? Configuration? A property of the file (like PDF vs epub)?