The belief that members of different castes cannot speak to each other is a gross exaggeration. The English word “caste” does have a connotation of strict separation. It’s from the Latin word castus, “pure, cut off, segregated” (see also castration), but in caste societies such as India there is a lot of interaction between members of different castes. It’s true that the Indian caste system still results in some level of segregation and discrimination between castes (even if the Indian Constitution has outlawed discrimination based on caste), but nothing like what is suggested by the above cartoon, which is almost racist and certainly a denigration of India. See this previous post for a more in-depth analysis of the Indian caste system.