No body was ever found in the trunk of the car, and no proof that a dead body was ever in the car.
Again, we don't know where, when, or how Caylee died.
No conviction was ever going to come without that knowledge. You can't put Casey at the scene of the murder when you don't know what happened. They couldn't place her at the remains of the corpse either.. hence, no murder conviction.
Its really not that difficult to understand, im not sure how this dicussion is still going on to be honest.
There are certain criteria that you are sworn to follow as a juror when arriving at your veridct. If the evidence doesn't satisfy all the criteria, you simply can't arrive at a guilty veridct. That's all. Its simply a bad prosecution and an embarassment for the state of Florida.