Maybe Indians have less contact with wildlife (due to different settlement patterns, or religious or cultural restrictions on eating wild animals?), or less average physical mobility (more expensive and inconvenient long-distance transportation), or a climate less conducive to certain modes of virus transmission?

A smaller fraction of the population working or commuting in huge indoor spaces?

Maybe (contrary to Americans' intuition) Chinese public health surveillance is both more effective and more transparent than Indian, leading to a measurement bias because some disease outbreaks that arise in China get better-documented?