People from lower castes care because they face discrimination, obviously. People from higher castes, even if they're open-minded on the topic of caste, likely

People from lower castes care because they face discrimination, obviously. People from higher castes, even if they're open-minded on the topic of caste, likely have relatives who aren't -- especially if they're the only member of a large family who has left India. Children have been disowned or even murdered by their relatives for marrying a member of a lower caste; it's really hard to escape that sort of prejudice.