title_body: Why publish technical books only in hardback form and not in ebook form?
upvoted_answer: One reason is that formatting a technical book for printing is 10x easier than formatting it for ebook. Often, people are using Adobe Indesign to handle the difficult formatting issues and while there is an epub export function, I'm guessing that it can't handle technical issues across platforms easily. When you print, you need only to worry about how the printed book looks. 
  
  Another issue to think about is that some technical books just work better as printed books. Stuff with lots of diagrams, indices, oversized pages. Sometimes programming books are hard to view as ebooks because the lines of code are hard to look at one page at a time while in printed books there is the possibility of having them on back to back pages. I have the wonderful Docbook XSL book by Bob Staynton, and even though the full book is online http://www.sagehill.net/docbookxsl/  I eventually bought a hard copy because I felt more comfortable putting paperclips on key pages and keeping it near my side as a reference. Some references work better in print form for that reason. 
  
  One final thought is that because Amazon decided not to sell PDFs and ibooks doesn't do so either, the publisher can't just sell PDFs except from their own stores. It involves setting up an Adobe content server which manages the DRM. That's a lot of unnecessary work. I suspect if Amazon sold PDFs directly or if a company like Scribd became more popular selling PDF, then this argument would disappear because publishers could just reuse the PDF they used for the print copy. 
  
  By the way, I used to say only a few years ago that PDF sucked because it wasn't reflowable and the tablet screens were not large enough. Now, fortunately, 10 inch screens and higher are much more common. so that is no longer a minus for using PDFs for reading it as an ebook.