Well, the Great Pilot Shortage   

They aren't fake but often they are not immediate need either, especially at major airlines. Regionals tend to be pretty responsive, but it's not rare to send in an application to a major airline and not hear anything for months, if ever.  Many airlines will open hiring windows where they simply collect applications, most often to fill a pool of applicants they can select for interviews at a later date.  After the interview process it still can take awhile to get a class date, and class dates can get cancelled if the training department can't handle the load, or if circumstances at the airline change.  It's important to remember as I mentioned before, you are not an airline pilot until you complete IOE, so don't burn any bridges and make any radical life changes based on your new job until completing IOE.  

Another type airline application process is the open application.  Regional airlines and airlines with historically a high turnover simply maintain an open application window regardless if they are currently hiring or not, because they expect attrition.  With these job postings you may apply and even interview, only to be placed in a pool for future class dates when they open up at an undetermined time in the future.  

So again while not fake, in many cases job postings are not to fill immediate needs either.