Charlie Jane Anders shines her illuminating prose on this seemingly paradoxical state of affairs:

by Charlie Jane Anders
Right now, it’s pilot season — which means you’re going to be hearing about a lot of TV shows getting ordered. And then, nine months from now… most of those shows will not be on television. What is this mysterious crucible? Here’s our step-by-step guide to the process of pitching a brand new television show.
Right about now, we ought to be in the middle of watching the first season of Hieroglyph, a show about gods in ancient Egypt that was “ordered to series” by Fox. But Fox pulled the plug on Hieroglyph, even after ordering a full season in advance, and we never even got to see it. That’s just one extreme example of a more common phenomenon — to casual observers, it looks like things are getting ordered all the time, then never showing up.