Why do u think that caste rules are rigid?

Caste rules were formed centuries ago when all the castes were formed. Every caste has its own customs. With time, some people started according more importance to the rules than the change in time. In various spheres, people progressed but the rules did not due to the stubbornness of the society. Apart from that, during the colonial era, the counting of caste and officially recording it made this institution of caste identity more rigid in India.