Why are there no left hand spinning reels?

You may have noticed that baitcasting reels are offered in right hand and left hand models, yet spinning reels aren't sold in a left hand configuration.  The question remains, and nobody seems to talk about it: Why are there no left handed spinning reels?

The short answer is because all spinning reels are left handed reels. 

All spinning reels are also right handed reels!  The functionality of a spinning reel is completeley independent of which side the crank handle is attached to.  Left or right, line spools or casts the same way, and since the drag is controlled via the front or rear of the reel (depending on manufacturer and model), it is also unaffected.  So it's possible for all spinning reels to have their handles swapped from side to side depending on the preference of the angler.  This also means that a right handed angler who prefers to control the rod with their right hand can utilize a left hand crank on their spinning reel.  

So why are baitcasting reels sold in left and right handed versions? 

Due to the way baitcasting reels are designed, their handles cannot be swapped from one side to the other.  The mechanisms that control drag and line retrieve are built in such a way that they can't be easily swapped to the other side of the reel.  So an angler has to commit to a left or right handed baitcasting reel.