Nice idea, but the problem with that is too often it would result in so much extra expense for lawyering and expert testimony and court time to prove what did what damage--or even how much more damage might have been done if person were belted--that it would probably be cheaper just to pay.
You may be right, but the responsibility for that rests with the legislatures and the courts. The purpose of contract law is to clarify responsibilities and reduce litigation. It was never intended to obtain "fairness", however that might be defined.
The statute of frauds concerning real estate dictates that all real estate transactions must be in writing. This may not be fair to those who rely on verbal agreements, but it serves the purpose of keeping these cases out of court without written contracts to enforce. Unfortunately, laws have been passed and judgements rendered in an attempt to be "fair" to people without such written contracts and thus the benefit of reducing litigation has been significantly reduced.
There are many ways that the legislatures could reform the tort system so that it is more "fair" to those who are not parties to litigation but it would require pre-judgements to eliminate the courts latitude. The lawyers will not allow this.