Answer:
Because the law of contract has to do with private law relation.
Explanation:
Given that law of contract has to deal with Private laws involving parties to the contract, but not in any way affecting or involving the state or society. The law of contract has seen so little constitutional transformation. For example law of the contract between manufacturers of cars and consumers or buyers.
This is evident in the fact that people's perception and the reality is that the outcomes of the successful delivery or breach of the law of contract have no direct implication on the other people in the society such as individual rights.