But enforcement has been spotty. The popularity of stickers—and the deference they can inspire—is partly a reflection of India’s longstanding caste system, in which some people command ...

Even in India, where the caste system was most rigid, the practice has been officially banned since 1950. Essentially, a caste system is a rigid assignment of social status based on inheritance.

More than 240 million people in South Asia live a precarious existence, shunned by much of society because of their ranks as untouchables or Dalits at the bottom of a rigid caste system.