Scientists rarely say theory is proven. they only only say whether the evidence

Scientists rarely say that a theory is proven. They will say that whether their the evidence presented supports the theory or not. This is because a scientific theory is subjected to change. Any new evidence found in contradiction to the previous theory will lead to the formation of another theory. Hence, a theory is no proved, it is supported through evidences or experiments.

In contrast, when an evidence is proved it will be subjected to become a scientific law. A scientific law cannot be changed.