Most PDF viewers I am aware of (including my own, PostView) have 2 up modes, are those not sufficient?

that's still presenting the pages in portrait orientation. I want the pages to be landscape and for the text to flow in at least 2 columns.

PDF is used primarily for pre-paginated media and does not reflow text; if the PDF author wanted the pages in landscape orientation, or using some other paper dimensions, he would have specified that. Same goes for margins and the like.

Doesn't mean the author isn't wrong for my reading situation... Or isn't doing it just cause everyone else is.

I think what the parent is trying to say is that PDF is not like HTML or text or other formats where the viewer is primarily responsible for a lot of the formatting --- in fact, a PDF page contains not much more than primitive instructions of the form "move to X, Y"; "set font to F"; "draw text 'Some text here'" (some pathological cases issue individual moves and draws for each character) --- so expecting all PDF viewers to be able to somehow "reverse-engineer" or "decompile" that set of low-level drawing instructions into more semantic entities like lines of text or even words in order to reformat the text is a little too much.

Anyone who has tried selecting text from a two-column PDF page will also quickly realise the nature of the problem.

I totally get that; however since these days a standard sheet of papers is no longer the main reading mechanism... I'm not sure it's the best layout for reading. My brother is a PhD and reads papers all day. He hates the two column format and paid for a reflowing reader. PDF is terrible on screens with different ratios than paper... Eg good computers and mobile. As I get older I use my plethora of giant screens to crank the fonts way up and sit back relaxed. PDF is terrible in that situation.

Just a thought... Maybe highly formatted PDFs for paper print shouldn't be the standard anymore. Eg my original point.

ok, that's what the author wanted, but they're wrong. We are reading our text on computers in 2017 - we should be able to choose the format that reads best for us.