Again... how would you do it though? Who would do the punishing? How would you enforce the punishment? Would clients build the punishment into the contract?

Again... how would you do it though? Who would do the punishing? How would you enforce the punishment? Would clients build the punishment into the contract? Even if you could do that, the vendors have the advantage of how to construct the contract in their best interests and avoid punishment. Most ideas will go straight back to market forces. Again, the issue is expertise to choose good options, not the existence of market forces.