To me Page count is simply a
uniform comparison tool.
By using the same setting on all books, I can quickly guestimate reading length between books. (Byte count is too easily distorted by Images and embedded fonts)
Other things that throw all guestimates off: Sample chapters, Other books by ads (w/cover images), publishers ads
Where's the Beef (just the main story)?
Almost as bad as books the us slightly bigger line-spacing (1.3 vs the standard 1.2) to make them appear to have more filling