That’s not how it works though all the defense is trying to show is that the prosecution’s case is flawed. They aren’t arguing separate narratives. They are arguing about that what the prosecution’s presentation of the facts mean in terms of the charges brought against the defendant. The only thing that they have to talk about in court is what is brought up by the government.
Because the all 12 of those fallible components need to agree unanimously to convict and punish one of their fellow citizens for the commission of crime. I know I rather have 12 get out of jail free cards rather than one.
Your right that our judicial system tends to allow otherwise guilty people go free, but that is the bargain we have made with each other so the government has a very hard time punishing innocent people.
The civil trial was the Goldman family vs OJ Simpson seeking monetary compensation for damages while the criminal trial was the People of California v OJ Simpson. A law suit has a different burden of proof for the determination of liability.