A well-prepared PDF can include metadata about each page, so that reader software will be able to display the "logical" page number in addition to the actual numerical index. E.g. a page in the prologue of a book might show up as "xvii (19 of 150)".

This is important because if you want to print a subset of pages, you have to specific the actual numerical page numbers in the print dialog, which may not be the same as the page number on the page.

Especially once the PDFs inevitably include scans of Something Else, or are constituted from multiple concatenated already-paginated extant documents.

This really is annoying. Maybe the solution is a smarter PDF reader that can detect the printed page numbers and use that for its own numbering?

Maybe pdf numbers are sightly annoying in the modern age of writing.